Overview

Multidrug-resistant organisms (MDROs)

• Multidrug resistance is considered when an isolate is resistant to at least 1 drug in 3 or more classes of medications.
• Organisms:
  • Vancomycin-resistant enterococci (VRE)
  • Methicillin-resistant Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus aureus (MRSA)
  • Extended spectrum beta-lactamase (ESBL)-producing organisms
  • Multidrug resistant gram-negative bacilli (MDRGNB) (especially carbapenem Carbapenem The carbapenems and aztreonam are both members of the bactericidal beta-lactam family of antibiotics (similar to penicillins). They work by preventing bacteria from producing their cell wall, ultimately leading to bacterial cell death. Carbapenems and Aztreonam-resistant bacilli and difficult-to-treat resistant Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa)

Hospital-acquired infection (HAI)

• Nosocomial infection
• An infection transmitted within a hospital or healthcare facility
• Infections:
  • Central line-associated bloodstream infection (CLABSI)
  • Catheter-associated urinary tract Urinary tract The urinary tract is located in the abdomen and pelvis and consists of the kidneys, ureters, urinary bladder, and urethra. The structures permit the excretion of urine from the body. Urine flows from the kidneys through the ureters to the urinary bladder and out through the urethra. Urinary Tract infection (CAUTI)
  • Ventilator-associated pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia (VAP) and hospital-acquired pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia (HAP)
  • Clostridioides difficile infection (CDI)
  • Surgical site infection ( SSI SSI Surgical site infection (SSI) is a type of surgical infection that occurs at or near a surgical incision within 30 days of the procedure or within 90 days if prosthetic material is implanted. Surgical site infections are classified according to the depth of involvement as superficial, deep, or organ/space. Surgical Site Infections)

Epidemiology

• United States:
  • Annually: ≥ 2.8 million people acquire antibiotic-resistant infections with ≥ 35,000 associated deaths.
  • In the year 2015: 687,000 HAIs in acute care hospitals and 72,000 associated deaths
• MDRO trends:
  • MRSA:
    • Between 1995 and 2001, hospital-acquired MRSA bloodstream infections in the United States increased from 22% to 57%.
    • With infection prevention measures, infection rates have declined yearly by 17% between 2005 and 2012.
  • VRE:
    • The early 1990s: accounted for approximately 15% of enterococcal isolates
    • The early 2000s: accounted for approximately 29% of enterococcal isolates
  • Gram-negative bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview resistant to fluoroquinolones Fluoroquinolones Fluoroquinolones are a group of broad-spectrum, bactericidal antibiotics inhibiting bacterial DNA replication. Fluoroquinolones cover gram-negative, anaerobic, and atypical organisms, as well as some gram-positive and multidrug-resistant (MDR) organisms. Fluoroquinolones, ESBLs, carbapenems, and aminoglycosides Aminoglycosides Aminoglycosides are a class of antibiotics including gentamicin, tobramycin, amikacin, neomycin, plazomicin, and streptomycin. The class binds the 30S ribosomal subunit to inhibit bacterial protein synthesis. Unlike other medications with a similar mechanism of action, aminoglycosides are bactericidal. Aminoglycosides have increased significantly over the last 2 decades.
• HAIs: 
  • Increased likelihood to be caused by antibiotic-resistant organisms
  • Urinary tract infections (UTIs) are the most common type of HAI.
  • 75% are associated with catheter use.
  • Up to 25% of hospitalized individuals receive urinary catheters.

Methicillin Resistant Staphylococcus Aureus (MRSA)

MRSA

• MRSA is a group of Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus aureus resistant to beta-lactam antibiotics including cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with "cef-" or "ceph-." Cephalosporins:
  • Oxacillin minimum inhibitory concentration ≥ 4 μg/mL
  • Community-associated MRSA infection (CA-MRSA): MRSA infection without healthcare exposure 
  • Healthcare-associated MRSA infection (HA-MRSA): 
    • MRSA infection > 48 hours following hospitalization; OR
    • MRSA infection outside the hospital within 12 months of healthcare exposure (e.g., surgery, hospitalization, dialysis Dialysis Renal replacement therapy refers to dialysis and/or kidney transplantation. Dialysis is a procedure by which toxins and excess water are removed from the circulation. Hemodialysis and peritoneal dialysis (PD) are the two types of dialysis, and their primary difference is the location of the filtration process (external to the body in hemodialysis versus inside the body for PD). Overview and Types of Dialysis)
• Mechanism of resistance:
  • MRSA resistance is due to the presence of a mec gene (required in methicillin resistance). 
  • The gene has a mecA component, which generates penicillin binding protein 2a (PBP2a):
    • PBP2a (peptidase enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body's constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes in the bacterial membrane) lowers the affinity for the organism to bind to beta-lactam antibiotics.
    • Detection of the mec gene and PBP2a is the most accurate way to determine methicillin resistance.
• Risk factors:
  • Healthcare-associated risk factors:
    • Recent hospitalization
    • Residence in a long-term care facility
    • Recent surgery
    • Hemodialysis
  • Additional risk factors:
    • HIV infection HIV infection Human immunodeficiency virus (HIV), a single-stranded RNA virus belonging to the Retroviridae family, is the etiologic agent of acquired immunodeficiency syndrome (AIDS). The human immunodeficiency virus is a sexually transmitted or blood-borne infection that attacks CD4+ T lymphocyte cells, macrophages, and dendritic cells, leading to eventual immunodeficiency. HIV Infection and AIDS
    • Injection drug use
    • Prior antibiotic use
  • Factors associated with MRSA outbreaks:
    • Incarceration
    • Military service
    • Sharing sports equipment
    • Sharing needles, razors, or other sharp objects

Infections and antibiotics

• Common infections:
  • Skin and soft tissue infections:
    • Cellulitis Cellulitis Cellulitis is a common infection caused by bacteria that affects the dermis and subcutaneous tissue of the skin. It is frequently caused by Staphylococcus aureus and Streptococcus pyogenes. The skin infection presents as an erythematous and edematous area with warmth and tenderness. Cellulitis
    • Necrotizing fasciitis Necrotizing fasciitis Necrotizing fasciitis is a life-threatening infection that causes rapid destruction and necrosis of the fascia and subcutaneous tissues. Patients may present with significant pain out of proportion to the presenting symptoms and rapidly progressive erythema of the affected area. Necrotizing Fasciitis
    • Diabetic foot ulcers
  • Bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Structure of Bones and joint infections:
    • Osteomyelitis Osteomyelitis Osteomyelitis is an infection of the bone that results from the spread of microorganisms from the blood (hematogenous), nearby infected tissue, or open wounds (non-hematogenous). Infections are most commonly caused by Staphylococcus aureus. Osteomyelitis of the spine
    • Osteomyelitis Osteomyelitis Osteomyelitis is an infection of the bone that results from the spread of microorganisms from the blood (hematogenous), nearby infected tissue, or open wounds (non-hematogenous). Infections are most commonly caused by Staphylococcus aureus. Osteomyelitis of long bones of the upper and lower extremities
    • Septic arthritis Septic arthritis Septic arthritis is an infection of the joint due to direct inoculation, contiguous extension, or hematogenous spread of infectious organisms into the joint space. This process causes an acute, inflammatory, monoarticular arthritis. Septic Arthritis of native and prosthetic joints
  • Pneumonia
  • Bacteremia
  • Endocarditis Endocarditis Endocarditis is an inflammatory disease involving the inner lining (endometrium) of the heart, most commonly affecting the cardiac valves. Both infectious and noninfectious etiologies lead to vegetations on the valve leaflets. Patients may present with nonspecific symptoms such as fever and fatigue. Endocarditis
• Antibiotic options:
  • Oral:
    • Trimethoprim Trimethoprim The sulfonamides are a class of antimicrobial drugs inhibiting folic acid synthesize in pathogens. The prototypical drug in the class is sulfamethoxazole. Although not technically sulfonamides, trimethoprim, dapsone, and pyrimethamine are also important antimicrobial agents inhibiting folic acid synthesis. The agents are often combined with sulfonamides, resulting in a synergistic effect. Sulfonamides and Trimethoprim, sulfamethoxazole
    • Tetracyclines Tetracyclines Tetracyclines are a class of broad-spectrum antibiotics indicated for a wide variety of bacterial infections. These medications bind the 30S ribosomal subunit to inhibit protein synthesis of bacteria. Tetracyclines cover gram-positive and gram-negative organisms, as well as atypical bacteria such as chlamydia, mycoplasma, spirochetes, and even protozoa. Tetracyclines: doxycycline, minocycline
    • Clindamycin
    • Oxazolidinones Oxazolidinones The oxazolidinones (linezolid and tedizolid) are bacterial protein synthesis inhibitors. Their unique binding site on the 23S ribosomal RNA of the 50S ribosome gives them zero cross-resistance with other antibiotics. Oxazolidinones: linezolid, tedizolid
    • Delafloxacin
  • Parenteral:
    • Vancomycin
    • Daptomycin
    • Dalbavancin
    • Oritavancin
    • Telavancin
    • Ceftaroline
    • Oxazolidinones Oxazolidinones The oxazolidinones (linezolid and tedizolid) are bacterial protein synthesis inhibitors. Their unique binding site on the 23S ribosomal RNA of the 50S ribosome gives them zero cross-resistance with other antibiotics. Oxazolidinones: linezolid, tedizolid
    • Delafloxacin

Prevention

• Hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand hygiene and contact precautions (e.g., gowns, gloves)
• Some healthcare institutions utilize active surveillance of individuals at high risk: 
  • Screening cultures of the nares, oropharynx, or perineum to identify individuals colonized with antibiotic-resistant bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview
  • Interventions may include decolonization, contact isolation, or comprehensive cleaning.
• Decolonization regimen can vary depending on circumstances (e.g., postdischarge, presurgery), but can include:
  • Chlorhexidine bath
  • Mupirocin nasal treatment
• Environmental cleaning
• Antibiotic stewardship (i.e., avoid excessive antibiotic use)

Vancomycin-Resistant Enterococci (VRE)

VRE

• Enterococcus Enterococcus Enterococcus is a genus of oval-shaped gram-positive cocci that are arranged in pairs or short chains. Distinguishing factors include optochin resistance and the presence of pyrrolidonyl arylamidase (PYR) and Lancefield D antigen. Enterococcus is part of the normal flora of the human GI tract. Enterococcus are resistant to vancomycin (most isolates are Enterococcus Enterococcus Enterococcus is a genus of oval-shaped gram-positive cocci that are arranged in pairs or short chains. Distinguishing factors include optochin resistance and the presence of pyrrolidonyl arylamidase (PYR) and Lancefield D antigen. Enterococcus is part of the normal flora of the human GI tract. Enterococcus faecium)
• Minimum inhibitory concentration (vancomycin resistant): ≥ 32 μg/mL
• Mechanism of resistance:
  • Vancomycin binds to the D-alanyl-D-alanine (D-Ala-D-Ala) terminus of bacterial cell wall precursors → disruption in bacterial cell wall synthesis
  • Resistance is due to modification of the D-Ala-D-Ala binding site of the peptidoglycan building block:
    • The terminal D-Ala is replaced by D-lactate → loss of hydrogen bond facilitating high-affinity binding of vancomycin to the target 
    • Encoded by several vancomycin-resistance gene clusters (i.e., vanA, vanB, vanC, vanD, and vanE)
• Risk factors:
  • Previous antimicrobial therapy (especially cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with "cef-" or "ceph-." Cephalosporins and vancomycin)
  • Hospitalization > 72 hours (especially ICU stay)
  • End-stage renal disease (ESRD) requiring dialysis Dialysis Renal replacement therapy refers to dialysis and/or kidney transplantation. Dialysis is a procedure by which toxins and excess water are removed from the circulation. Hemodialysis and peritoneal dialysis (PD) are the two types of dialysis, and their primary difference is the location of the filtration process (external to the body in hemodialysis versus inside the body for PD). Overview and Types of Dialysis
  • Transplant recipients
  • Proton pump inhibitor use
  • Invasive devices
  • Contaminated surfaces or equipment (e.g., thermometers, bedrails)
  • Residence in long-term care facilities

Infections and antibiotics

• Common infection types:
  • Bacteremia
  • Endocarditis Endocarditis Endocarditis is an inflammatory disease involving the inner lining (endometrium) of the heart, most commonly affecting the cardiac valves. Both infectious and noninfectious etiologies lead to vegetations on the valve leaflets. Patients may present with nonspecific symptoms such as fever and fatigue. Endocarditis
  • UTI UTI Urinary tract infections (UTIs) represent a wide spectrum of diseases, from self-limiting simple cystitis to severe pyelonephritis that can result in sepsis and death. Urinary tract infections are most commonly caused by Escherichia coli, but may also be caused by other bacteria and fungi. Urinary Tract Infections
• Antibiotic options:
  • Linezolid
  • Daptomycin
  • Tigecycline
  • Oritavancin
  • Teicoplanin
  • Telavancin

Prevention

• Hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand hygiene and contact precautions
• Chlorhexidine bath (benefit most noted in ICU admissions)
• Surveillance cultures for VRE in high-risk individuals:
  • Samples obtained from rectal swabs, perirectal swabs, stool sample, areas of skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin breakdown, and draining wounds
  • Healthcare workers may spread infection to other individuals: Appropriate isolation and contact measures are instituted with positive cultures.
• Environmental cleaning

Extended Spectrum Beta-Lactamase (ESBL)

ESBL

• Beta-lactamases or enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body's constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes expressed in organisms resistant to penicillins Penicillins Beta-lactam antibiotics contain a beta-lactam ring as a part of their chemical structure. Drugs in this class include penicillin G and V, penicillinase-sensitive and penicillinase-resistant penicillins, cephalosporins, carbapenems, and aztreonam. Penicillins, cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with "cef-" or "ceph-." Cephalosporins, and aztreonam Aztreonam The carbapenems and aztreonam are both members of the bactericidal beta-lactam family of antibiotics (similar to penicillins). They work by preventing bacteria from producing their cell wall, ultimately leading to bacterial cell death. Carbapenems and Aztreonam (a monobactam)
• Beta-lactamases open the beta-lactam ring, leading to antibiotic activation.
• Generally found in gram-negative organisms, predominantly in:
  • Klebsiella Klebsiella Klebsiella are encapsulated gram-negative, lactose-fermenting bacilli. They form pink colonies on MacConkey agar due to lactose fermentation. The main virulence factor is a polysaccharide capsule. Klebsiella pneumoniae is the most important pathogenic species. Klebsiella pneumoniae
  • Klebsiella Klebsiella Klebsiella are encapsulated gram-negative, lactose-fermenting bacilli. They form pink colonies on MacConkey agar due to lactose fermentation. The main virulence factor is a polysaccharide capsule. Klebsiella pneumoniae is the most important pathogenic species. Klebsiella oxytoca
  • Escherichia coli Escherichia coli The gram-negative bacterium Escherichia coli is a key component of the human gut microbiota. Most strains of E. coli are avirulent, but occasionally they escape the GI tract, infecting the urinary tract and other sites. Less common strains of E. coli are able to cause disease within the GI tract, most commonly presenting as abdominal pain and diarrhea. Escherichia coli
  • Proteus Proteus Proteus spp. are gram-negative, facultatively anaerobic bacilli. Different types of infection result from Proteus, but the urinary tract is the most common site. The majority of cases are caused by Proteus mirabilis (P. mirabilis). The bacteria are part of the normal intestinal flora and are also found in the environment. Enterobacteriaceae: Proteus mirabilis
• Mechanism of resistance:
  • Production of beta-lactamase enzyme leads to resistance to most beta-lactam antibiotics.
  • ESBLs have different varieties:
    • TEM beta-lactamases: Amino acid Amino acid Amino acids (AAs) are composed of a central carbon atom attached to a carboxyl group, an amino group, a hydrogen atom, and a side chain (R group). Basics of Amino Acids substitutions produce enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body's constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes, which hydrolyze penicillins Penicillins Beta-lactam antibiotics contain a beta-lactam ring as a part of their chemical structure. Drugs in this class include penicillin G and V, penicillinase-sensitive and penicillinase-resistant penicillins, cephalosporins, carbapenems, and aztreonam. Penicillins and narrow-spectrum cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with "cef-" or "ceph-." Cephalosporins.
    • SHV beta-lactamases: amino acid substitutions
    • CTX-M beta-lactamases: arise from plasmid acquisition of beta-lactamase genes
• Risk factors:
  • Hospitalization
  • Residence in a long-term care facility
  • Hemodialysis use
  • Presence of an intravascular catheter
  • Recent antibiotic therapy
  • Use of corticosteroids
  • Presence of a percutaneous feeding tube

Infections and antibiotics

• Common infection types:
  • Bacteremia
  • UTI UTI Urinary tract infections (UTIs) represent a wide spectrum of diseases, from self-limiting simple cystitis to severe pyelonephritis that can result in sepsis and death. Urinary tract infections are most commonly caused by Escherichia coli, but may also be caused by other bacteria and fungi. Urinary Tract Infections
  • Pneumonia
• Antibiotic options:
  • Carbapenems:
    • Imipenem
    • Meropenem
    • Doripenem
    • Ertapenem
  • Combination cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with "cef-" or "ceph-." Cephalosporins–beta-lactamase inhibitor agents:
    • Ceftolozane-tazobactam
    • Ceftazidime-avibactam
  • Piperacillin-tazobactam (for isolated UTIs)
  • Fosfomycin and nitrofurantoin (for simple cystitis)

Prevention

• Contact precautions
• Antibiotic restrictions (beta-lactam drugs)
• Environmental cleaning

Multidrug Resistant Gram-Negative Bacilli (MDRGNB)

MDRGNB

• Gram-negative bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview resistant to a number of antibiotics include: 
  • Acinetobacter baumannii: 67% resistant to carbapenems
  • Enterobacter spp: 37% resistant to 3rd or 4th generation cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with "cef-" or "ceph-." Cephalosporins
  • Escherichia coli Escherichia coli The gram-negative bacterium Escherichia coli is a key component of the human gut microbiota. Most strains of E. coli are avirulent, but occasionally they escape the GI tract, infecting the urinary tract and other sites. Less common strains of E. coli are able to cause disease within the GI tract, most commonly presenting as abdominal pain and diarrhea. Escherichia coli:
    • 42% resistant to fluoroquinolones Fluoroquinolones Fluoroquinolones are a group of broad-spectrum, bactericidal antibiotics inhibiting bacterial DNA replication. Fluoroquinolones cover gram-negative, anaerobic, and atypical organisms, as well as some gram-positive and multidrug-resistant (MDR) organisms. Fluoroquinolones
    • 19% resistant to 3rd or 4th generation cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with "cef-" or "ceph-." Cephalosporins
    • 2% resistant to carbapenems
  • Klebsiella Klebsiella Klebsiella are encapsulated gram-negative, lactose-fermenting bacilli. They form pink colonies on MacConkey agar due to lactose fermentation. The main virulence factor is a polysaccharide capsule. Klebsiella pneumoniae is the most important pathogenic species. Klebsiella pneumoniae:
    • 29% resistant to 3rd or 4th generation cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with "cef-" or "ceph-." Cephalosporins
    • 13% resistant to carbapenems 
  • Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa:
    • 31% resistant to fluoroquinolones Fluoroquinolones Fluoroquinolones are a group of broad-spectrum, bactericidal antibiotics inhibiting bacterial DNA replication. Fluoroquinolones cover gram-negative, anaerobic, and atypical organisms, as well as some gram-positive and multidrug-resistant (MDR) organisms. Fluoroquinolones
    • 26% resistant to 3rd or 4th generation cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with "cef-" or "ceph-." Cephalosporins
    • 26% resistant to carbapenems
• Mechanisms of resistance: 
  • Gram-negative bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview have innate resistance (exhibit no response to vancomycin due to the inability of the drug to penetrate the outer membrane).
  • Some produce beta-lactamases.
  • Biofilm formation (reduces diffusion of antimicrobial agent)
  • Resistance genes (can be transferred between bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview via vectors (e.g., plasmids, transposons)):
    • Produce antibiotic-inactivating enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body's constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes such as carbapenemases, which leads to carbapenem Carbapenem The carbapenems and aztreonam are both members of the bactericidal beta-lactam family of antibiotics (similar to penicillins). They work by preventing bacteria from producing their cell wall, ultimately leading to bacterial cell death. Carbapenems and Aztreonam resistance
    • Others downregulate the outer membrane protein OprD (a carbapenem Carbapenem The carbapenems and aztreonam are both members of the bactericidal beta-lactam family of antibiotics (similar to penicillins). They work by preventing bacteria from producing their cell wall, ultimately leading to bacterial cell death. Carbapenems and Aztreonam-specific porin), decreasing diffusion of the antibiotic.
    • Drug efflux pumps are created, which expel antimicrobial agents.
    • Transfer of a 16S rRNA methylase gene from Actinomycetes to Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa confer aminoglycoside resistance
• Risk factors include:
  • ICU stay
  • Chronic hemodialysis
  • Transplant recipients
  • Frequent use of certain antibiotics (e.g., broad-spectrum cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with "cef-" or "ceph-." Cephalosporins, aminoglycosides Aminoglycosides Aminoglycosides are a class of antibiotics including gentamicin, tobramycin, amikacin, neomycin, plazomicin, and streptomycin. The class binds the 30S ribosomal subunit to inhibit bacterial protein synthesis. Unlike other medications with a similar mechanism of action, aminoglycosides are bactericidal. Aminoglycosides, carbapenems, fluoroquinolones Fluoroquinolones Fluoroquinolones are a group of broad-spectrum, bactericidal antibiotics inhibiting bacterial DNA replication. Fluoroquinolones cover gram-negative, anaerobic, and atypical organisms, as well as some gram-positive and multidrug-resistant (MDR) organisms. Fluoroquinolones)
  • Diabetes mellitus Diabetes mellitus Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus
  • Liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver failure
  • Pulmonary disease
  • Albumin < 3 g/dL
  • HIV

Carbapenem-Resistant Enterobacterales (CRE)

• Organisms in the order:
  • Are resistant to ≥ 1 carbapenem Carbapenem The carbapenems and aztreonam are both members of the bactericidal beta-lactam family of antibiotics (similar to penicillins). They work by preventing bacteria from producing their cell wall, ultimately leading to bacterial cell death. Carbapenems and Aztreonam antibiotic
  • Produce a carbapenemase enzyme ( Klebsiella Klebsiella Klebsiella are encapsulated gram-negative, lactose-fermenting bacilli. They form pink colonies on MacConkey agar due to lactose fermentation. The main virulence factor is a polysaccharide capsule. Klebsiella pneumoniae is the most important pathogenic species. Klebsiella pneumoniae carbapenemases are the most common carbapenemase in the United States)
• Common infection types:
  • VAP
  • Bacteremia
  • Intra-abdominal abscesses
  • UTIs (e.g., cystitis, pyelonephritis Pyelonephritis Pyelonephritis is infection affecting the renal pelvis and the renal parenchyma. This condition arises mostly as a complication of bladder infection that ascends to the upper urinary tract. Pyelonephritis can be acute or chronic (which results from persistent or chronic infections). Typical acute symptoms are flank pain, fever, and nausea with vomiting. T Pyelonephritis and Perinephric Abscess)
• Antibiotic options:
  • Treatment is limited, especially for serious infections (e.g., bacteremia).
  • Resistance genes for other antibiotics are often present.
  • For infections resistant to ertapenem, but susceptible to meropenem:
    • Extended infusion meropenem can be used.
    • If carbapenemase testing is positive, do not use meropenem (even if susceptibility is positive).
  • For uncomplicated cystitis:
    • Ciprofloxacin, levofloxacin
    • Trimethoprim Trimethoprim The sulfonamides are a class of antimicrobial drugs inhibiting folic acid synthesize in pathogens. The prototypical drug in the class is sulfamethoxazole. Although not technically sulfonamides, trimethoprim, dapsone, and pyrimethamine are also important antimicrobial agents inhibiting folic acid synthesis. The agents are often combined with sulfonamides, resulting in a synergistic effect. Sulfonamides and Trimethoprim-sulfamethoxazole
    • Nitrofurantoin
    • Single-dose aminoglycoside
  • Complicated UTIs and infections outside the urinary tract Urinary tract The urinary tract is located in the abdomen and pelvis and consists of the kidneys, ureters, urinary bladder, and urethra. The structures permit the excretion of urine from the body. Urine flows from the kidneys through the ureters to the urinary bladder and out through the urethra. Urinary Tract:
    • Ceftazidime-avibactam
    • Meropenem-vaborbactam
    • Imipenem-cilastatin-relebactam
    • Cefiderocol

Difficult-to-treat resistant Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa

• Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa not susceptible to the following: 
  • Piperacillin-tazobactam
  • Ceftazidime, cefepime
  • Aztreonam
  • Meropenem, imipenem-cilastatin
  • Ciprofloxacin, levofloxacin
• Infections:
  • VAP
  • UTI UTI Urinary tract infections (UTIs) represent a wide spectrum of diseases, from self-limiting simple cystitis to severe pyelonephritis that can result in sepsis and death. Urinary tract infections are most commonly caused by Escherichia coli, but may also be caused by other bacteria and fungi. Urinary Tract Infections
  • Device-related infection (e.g., catheter)
  • Wounds or burns Burns A burn is a type of injury to the skin and deeper tissues caused by exposure to heat, electricity, chemicals, friction, or radiation. Burns are classified according to their depth as superficial (1st-degree), partial-thickness (2nd-degree), full-thickness (3rd-degree), and 4th-degree burns. Burns
• Antibiotic options:
  • Ceftolozane-tazobactam
  • Ceftazidime-avibactam
  • Imipenem-cilastatin-relebactam
  • Cefiderocol

Prevention

• Hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand hygiene
• Isolation precautions
• Antibiotic stewardship
• Environmental cleaning

Central Line-Associated Bloodstream Infection (CLABSI)

CLABSI

• Infection related to the placement or prolonged use of a central venous catheter Central Venous Catheter Central venous catheters are IV lines placed into the large central veins for monitoring of central venous pressure (CVP), prolonged drug administration, or administration of parenteral nutrition. The most common sites of insertion are the internal jugular and subclavian veins. Central Venous Catheter: Technique
• Risk factors:
  • Host factors:
    • Chronic illness
    • Bone marrow Bone marrow Bone marrow, the primary site of hematopoiesis, is found in the cavities of cancellous bones and the medullary canals of long bones. There are 2 types: red marrow (hematopoietic with abundant blood cells) and yellow marrow (predominantly filled with adipocytes). Composition of Bone Marrow transplantation
    • Immune deficiency (especially neutropenia Neutropenia Neutrophils are an important component of the immune system and play a significant role in the eradication of infections. Low numbers of circulating neutrophils, referred to as neutropenia, predispose the body to recurrent infections or sepsis, though patients can also be asymptomatic. Neutropenia)
    • Malnutrition Malnutrition Malnutrition is a clinical state caused by an imbalance or deficiency of calories and/or micronutrients and macronutrients. The 2 main manifestations of acute severe malnutrition are marasmus (total caloric insufficiency) and kwashiorkor (protein malnutrition with characteristic edema). Malnutrition in children in resource-limited countries
    • Total parenteral nutrition administration
    • Previous bloodstream infections
    • Extremes of age
    • Loss of skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin integrity (e.g., burns Burns A burn is a type of injury to the skin and deeper tissues caused by exposure to heat, electricity, chemicals, friction, or radiation. Burns are classified according to their depth as superficial (1st-degree), partial-thickness (2nd-degree), full-thickness (3rd-degree), and 4th-degree burns. Burns)
  • Catheter factors:
    • Location of catheter (e.g., subclavian catheter carries less risk)
    • Duration of catheterization
    • Type of catheter (e.g., non-tunneled catheters carry higher risk of infection)
    • Conditions of insertion
    • Catheter site care
    • Skill of operator performing insertion
• Sources of infection:
  • Skin colonization
  • Intraluminal contamination
  • Hematogenous seeding
  • Infusate contamination
• Common organisms:
  • Coagulase-negative staphylococci (CoNS)
  • Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus aureus
  • Enterococcus Enterococcus Enterococcus is a genus of oval-shaped gram-positive cocci that are arranged in pairs or short chains. Distinguishing factors include optochin resistance and the presence of pyrrolidonyl arylamidase (PYR) and Lancefield D antigen. Enterococcus is part of the normal flora of the human GI tract. Enterococcus
  • Candida Candida Candida is a genus of dimorphic, opportunistic fungi. Candida albicans is part of the normal human flora and is the most common cause of candidiasis. The clinical presentation varies and can include localized mucocutaneous infections (e.g., oropharyngeal, esophageal, intertriginous, and vulvovaginal candidiasis) and invasive disease (e.g., candidemia, intraabdominal abscess, pericarditis, and meningitis). Candida/Candidiasis spp
  • Klebsiella Klebsiella Klebsiella are encapsulated gram-negative, lactose-fermenting bacilli. They form pink colonies on MacConkey agar due to lactose fermentation. The main virulence factor is a polysaccharide capsule. Klebsiella pneumoniae is the most important pathogenic species. Klebsiella spp
  • Escherichia coli Escherichia coli The gram-negative bacterium Escherichia coli is a key component of the human gut microbiota. Most strains of E. coli are avirulent, but occasionally they escape the GI tract, infecting the urinary tract and other sites. Less common strains of E. coli are able to cause disease within the GI tract, most commonly presenting as abdominal pain and diarrhea. Escherichia coli
  • Enterobacter spp
  • Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas spp

Antibiotics and management

• Empiric therapy:
  • Gram-positive organisms: vancomycin
  • Gram-negative bacilli if no hemodynamic instability, neutropenia Neutropenia Neutrophils are an important component of the immune system and play a significant role in the eradication of infections. Low numbers of circulating neutrophils, referred to as neutropenia, predispose the body to recurrent infections or sepsis, though patients can also be asymptomatic. Neutropenia, or burns Burns A burn is a type of injury to the skin and deeper tissues caused by exposure to heat, electricity, chemicals, friction, or radiation. Burns are classified according to their depth as superficial (1st-degree), partial-thickness (2nd-degree), full-thickness (3rd-degree), and 4th-degree burns. Burns present: ceftriaxone
  • Gram-negative bacilli if hemodynamic instability, neutropenia Neutropenia Neutrophils are an important component of the immune system and play a significant role in the eradication of infections. Low numbers of circulating neutrophils, referred to as neutropenia, predispose the body to recurrent infections or sepsis, though patients can also be asymptomatic. Neutropenia, or severe burns Burns A burn is a type of injury to the skin and deeper tissues caused by exposure to heat, electricity, chemicals, friction, or radiation. Burns are classified according to their depth as superficial (1st-degree), partial-thickness (2nd-degree), full-thickness (3rd-degree), and 4th-degree burns. Burns present (use antipseudomonal agents): 
    • Ceftazidime, cefepime
    • Piperacillin-tazobactam
    • Imipenem, meropenem
• Directed therapy for Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus:
  • Methicillin susceptible:
    • Nafcillin
    • Oxacillin
    • Cefazolin
    • Flucloxacillin
  • Methicillin resistant:
    • Vancomycin
    • Daptomycin
• Directed therapy for Enterococcus Enterococcus Enterococcus is a genus of oval-shaped gram-positive cocci that are arranged in pairs or short chains. Distinguishing factors include optochin resistance and the presence of pyrrolidonyl arylamidase (PYR) and Lancefield D antigen. Enterococcus is part of the normal flora of the human GI tract. Enterococcus:
  • Ampicillin susceptible: ampicillin
  • Ampicillin resistant, vancomycin susceptible: vancomycin
  • Ampicillin resistant, vancomycin resistant: daptomycin, linezolid
• Enterobacteriaceae (e.g., Escherichia coli, Klebsiella Klebsiella Klebsiella are encapsulated gram-negative, lactose-fermenting bacilli. They form pink colonies on MacConkey agar due to lactose fermentation. The main virulence factor is a polysaccharide capsule. Klebsiella pneumoniae is the most important pathogenic species. Klebsiella spp, Enterobacter spp):
  • ESBL negative:
    • Ceftriaxone
    • Ciprofloxacin
  • ESBL positive:
    • Imipenem
    • Meropenem
    • Ertapenem
    • Ciprofloxacin
• Pseudomonas spp:
  • Preferred:
    • Ceftazidime
    • Cefepime
    • Piperacillin-tazobactam
  • Alternative:
    • Imipenem
    • Meropenem
    • Ciprofloxacin
• Catheter management:
  • Remove in the following cases:
    • Hemodynamic instability
    • Sepsis
    • Blood clot or suppurative thrombophlebitis
    • Endocarditis Endocarditis Endocarditis is an inflammatory disease involving the inner lining (endometrium) of the heart, most commonly affecting the cardiac valves. Both infectious and noninfectious etiologies lead to vegetations on the valve leaflets. Patients may present with nonspecific symptoms such as fever and fatigue. Endocarditis
    • Subcutaneously tunneled central venous catheter Central Venous Catheter Central venous catheters are IV lines placed into the large central veins for monitoring of central venous pressure (CVP), prolonged drug administration, or administration of parenteral nutrition. The most common sites of insertion are the internal jugular and subclavian veins. Central Venous Catheter: Technique tract infection or subcutaneous port reservoir infection
    • Bacteremia persists even after 72 hours of appropriate antibiotics.
    • Organisms identified: Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus aureus, Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa, MDRGNB, or Candida Candida Candida is a genus of dimorphic, opportunistic fungi. Candida albicans is part of the normal human flora and is the most common cause of candidiasis. The clinical presentation varies and can include localized mucocutaneous infections (e.g., oropharyngeal, esophageal, intertriginous, and vulvovaginal candidiasis) and invasive disease (e.g., candidemia, intraabdominal abscess, pericarditis, and meningitis). Candida/Candidiasis spp
  • Salvage in the following cases:
    • Uncomplicated infection from CoNS
    • Does not generally involve orthopedic hardware or endovascular implant
    • Antibiotic lock therapy (antibiotic instillation in the lumen) with systemic antibiotics given

Prevention

• Handwashing
• Full barrier precautions with insertion of central venous catheter Central Venous Catheter Central venous catheters are IV lines placed into the large central veins for monitoring of central venous pressure (CVP), prolonged drug administration, or administration of parenteral nutrition. The most common sites of insertion are the internal jugular and subclavian veins. Central Venous Catheter: Technique
• Chlorhexidine for skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin disinfection
• Avoidance of the femoral insertion site 
• Removal of catheters when no longer indicated

Catheter-Associated Urinary Tract Infection (CAUTI)

CAUTI

• A urinary infection related to the use of a urinary catheter (foley catheter)
• Differentiation according to the Infectious Diseases Society of America:
  • Symptomatic bacteriuria ( UTI UTI Urinary tract infections (UTIs) represent a wide spectrum of diseases, from self-limiting simple cystitis to severe pyelonephritis that can result in sepsis and death. Urinary tract infections are most commonly caused by Escherichia coli, but may also be caused by other bacteria and fungi. Urinary Tract Infections): 
    • Culture growth of ≥ 10³ colony forming units (CFU)/mL of uropathogenic bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview
    • UTI UTI Urinary tract infections (UTIs) represent a wide spectrum of diseases, from self-limiting simple cystitis to severe pyelonephritis that can result in sepsis and death. Urinary tract infections are most commonly caused by Escherichia coli, but may also be caused by other bacteria and fungi. Urinary Tract Infections signs and symptoms without another identifiable source
    • Symptoms can include fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, suprapubic or costovertebral angle tenderness, altered mental status, and hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension.
    • Indwelling urethral, indwelling suprapubic, or intermittent catheterization currently or within 48 hours
  • Asymptomatic bacteriuria:
    • Culture growth of ≥ 10⁵ CFU/mL of uropathogenic bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview
    • No UTI UTI Urinary tract infections (UTIs) represent a wide spectrum of diseases, from self-limiting simple cystitis to severe pyelonephritis that can result in sepsis and death. Urinary tract infections are most commonly caused by Escherichia coli, but may also be caused by other bacteria and fungi. Urinary Tract Infections symptoms noted in an individual with indwelling urethral, indwelling suprapubic, or intermittent catheterization
• Risk factors:
  • Longer duration of catheterization
  • Female
  • Older age
  • Diabetes mellitus Diabetes mellitus Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus
  • Drainage bag is colonized by bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview.
  • Catheter maintenance problems (i.e., errors in sterile technique, not maintaining a closed drainage system)
• Pathogenesis:
  • Extraluminal (more common): Bacteria enter the bladder along the biofilm (forms around the catheter).
  • Intraluminal: drainage failure (promotes urinary stasis or ascending infection from a contaminated urine collection bag)
• Common organisms:
  • Escherichia coli
  • Candida Candida Candida is a genus of dimorphic, opportunistic fungi. Candida albicans is part of the normal human flora and is the most common cause of candidiasis. The clinical presentation varies and can include localized mucocutaneous infections (e.g., oropharyngeal, esophageal, intertriginous, and vulvovaginal candidiasis) and invasive disease (e.g., candidemia, intraabdominal abscess, pericarditis, and meningitis). Candida/Candidiasis spp
  • Enterococcus Enterococcus Enterococcus is a genus of oval-shaped gram-positive cocci that are arranged in pairs or short chains. Distinguishing factors include optochin resistance and the presence of pyrrolidonyl arylamidase (PYR) and Lancefield D antigen. Enterococcus is part of the normal flora of the human GI tract. Enterococcus spp
  • Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa
  • Klebsiella Klebsiella Klebsiella are encapsulated gram-negative, lactose-fermenting bacilli. They form pink colonies on MacConkey agar due to lactose fermentation. The main virulence factor is a polysaccharide capsule. Klebsiella pneumoniae is the most important pathogenic species. Klebsiella spp

Management

• Antimicrobial options:
  • Depend on culture and susceptibility results
  • Require consideration of the following factors:
    • Past urine cultures
    • Prior antimicrobial therapy
    • Healthcare exposures
    • Prevalence of antimicrobial resistance
    • Antibiotic allergies
• Minimize use of indwelling catheters:
  • Intermittent catheterization carries a lower risk of UTI UTI Urinary tract infections (UTIs) represent a wide spectrum of diseases, from self-limiting simple cystitis to severe pyelonephritis that can result in sepsis and death. Urinary tract infections are most commonly caused by Escherichia coli, but may also be caused by other bacteria and fungi. Urinary Tract Infections.
  • If an indwelling catheter is necessary, replacement is recommended along with the initiation of antibiotics.
• Prevention:
  • Avoid unnecessary catheterization.
  • Use sterile techniques while placing the catheter.
  • Remove the catheter as soon as no longer needed.

Nosocomial and Ventilator-Associated Pneumonias (VAPs)

Pneumonias in the hospital

• Definitions:
  • HAP or nosocomial pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia: lung infection occurring ≥ 48 hours after admission and not incubating at the time of admission
  • VAP: pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia developing ≥ 48 hours after endotracheal intubation
• Risk factors:
  • Mechanical ventilation: Most HAPs occur in individuals not on mechanical ventilation (mechanically ventilated individuals carry the highest risk of HAP).
  • Older age
  • Chronic lung disease
  • Depressed consciousness
  • Aspiration
  • Chest or upper abdominal surgery
  • Agents that increase gastric pH
  • Previous antibiotic exposure (especially broad-spectrum antibiotics)
  • Reintubation or prolonged intubation
  • Increased opioid use
  • Trauma
  • Paralysis
  • Numerous central venous catheter Central Venous Catheter Central venous catheters are IV lines placed into the large central veins for monitoring of central venous pressure (CVP), prolonged drug administration, or administration of parenteral nutrition. The most common sites of insertion are the internal jugular and subclavian veins. Central Venous Catheter: Technique placements and surgeries
  • Use of muscle relaxants or glucocorticoids Glucocorticoids Glucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs. Glucocorticoids
  • Presence of an intracranial pressure monitor
  • Malnutrition Malnutrition Malnutrition is a clinical state caused by an imbalance or deficiency of calories and/or micronutrients and macronutrients. The 2 main manifestations of acute severe malnutrition are marasmus (total caloric insufficiency) and kwashiorkor (protein malnutrition with characteristic edema). Malnutrition in children in resource-limited countries
  • Chronic renal failure
  • Anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview
  • Previous hospitalization
• Common organisms:
  • Gram-negative bacilli:
    • Escherichia coli Escherichia coli The gram-negative bacterium Escherichia coli is a key component of the human gut microbiota. Most strains of E. coli are avirulent, but occasionally they escape the GI tract, infecting the urinary tract and other sites. Less common strains of E. coli are able to cause disease within the GI tract, most commonly presenting as abdominal pain and diarrhea. Escherichia coli
    • Klebsiella Klebsiella Klebsiella are encapsulated gram-negative, lactose-fermenting bacilli. They form pink colonies on MacConkey agar due to lactose fermentation. The main virulence factor is a polysaccharide capsule. Klebsiella pneumoniae is the most important pathogenic species. Klebsiella pneumoniae
    • Enterobacter spp
    • Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa
    • Acinetobacter spp
• Gram-positive bacilli:
  • Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus aureus (including MRSA)
  • Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus spp

Management

• Antibiotic options:
  • Include coverage for:
    • Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus aureus
    • Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa
    • Other gram-negative bacilli
  • Consider local pathogens and risks for MDROs.
• Regimen:
  • Individuals with no risk for MDRO and low risk for MRSA: 1 agent against Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa, other GNB, and methicillin-sensitive Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus aureus:
    • Piperacillin-tazobactam
    • Cefepime
    • Levofloxacin 
  • Individuals at risk for MDRO (including MRSA): 2 agents against Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa and other GNB, and 1 agent with activity against MRSA:
    • Piperacillin-tazobactam/cefepime/ceftazidime/ carbapenem Carbapenem The carbapenems and aztreonam are both members of the bactericidal beta-lactam family of antibiotics (similar to penicillins). They work by preventing bacteria from producing their cell wall, ultimately leading to bacterial cell death. Carbapenems and Aztreonam/ aztreonam Aztreonam The carbapenems and aztreonam are both members of the bactericidal beta-lactam family of antibiotics (similar to penicillins). They work by preventing bacteria from producing their cell wall, ultimately leading to bacterial cell death. Carbapenems and Aztreonam; AND, 
    • An aminoglycoside (e.g., amikacin, gentamicin); AND,
    • Vancomycin/linezolid/telavancin
• Prevention:
  • Use of non-invasive positive pressure ventilation when possible (avoiding intubation)
  • Weaning protocols
  • Minimize sedation
  • Facilitate physical conditioning and early mobility
  • Prevent aspiration:
    • Bed elevation
    • Drainage of subglottic secretions
  • Approaches to help lower VAP:
    • Probiotics
    • Oral care (chlorhexidine)
    • Stress ulcer prophylaxis
    • Silver-coated endotracheal tubes

Clostridioides difficile Infection (CDI)

CDI

• Infection caused by the spore-forming bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview Clostridioides difficile
• One of the most common hospital-acquired infections
• Risk factors:
  • Antibiotic use
  • Advanced age
  • Hospitalization
  • Severe comorbid illness
• Microbiology and disease:
  • Clostridioides difficile:
    • Anaerobic gram-positive, spore-forming, toxin-producing bacillus Bacillus Bacillus are aerobic, spore-forming, gram-positive bacilli. Two pathogenic species are Bacillus anthracis (B. anthracis) and B. cereus. Bacillus
    • Releases 2 potent exotoxins that mediate colitis and diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea: enterotoxin A ( diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea) and toxin B ( pseudomembranous colitis Pseudomembranous colitis Pseudomembranous colitis is a bacterial disease of the colon caused by Clostridium difficile. Pseudomembranous colitis is characterized by mucosal inflammation and is acquired due to antimicrobial use and the consequent disruption of the normal colonic microbiota. C. difficile infections account for the most commonly diagnosed hospital-acquired diarrheal illnesses. Pseudomembranous Colitis)
  • Pseudomembranous colitis (severe inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the bowel lining):
    • Abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain
    • Profuse watery diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea (may occasionally be bloody)
    • Leukocytosis
    • Associated with recent antibiotic use (e.g., clindamycin, fluoroquinolones Fluoroquinolones Fluoroquinolones are a group of broad-spectrum, bactericidal antibiotics inhibiting bacterial DNA replication. Fluoroquinolones cover gram-negative, anaerobic, and atypical organisms, as well as some gram-positive and multidrug-resistant (MDR) organisms. Fluoroquinolones, cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with "cef-" or "ceph-." Cephalosporins, penicillins Penicillins Beta-lactam antibiotics contain a beta-lactam ring as a part of their chemical structure. Drugs in this class include penicillin G and V, penicillinase-sensitive and penicillinase-resistant penicillins, cephalosporins, carbapenems, and aztreonam. Penicillins)

Management

• Antibiotic options:
  • Oral fidaxomicin
  • Oral vancomycin
  • Metronidazole
• Recurrent CDI: Add bezlotoxumab (monoclonal antibody).
• Discontinue the inciting antibiotic.
• Supportive care: Manage fluid and electrolyte losses.
• Other:
  • Fecal microbiota transplant (FMT):
    • Processed stool from a healthy donor is instilled into the intestinal tract.
    • Administered via oral capsules, colonoscopy, retention enema, or a nasojejunal/nasoduodenal tube
  • Consider surgery in the case of fulminant disease (i.e., hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension, shock Shock Shock is a life-threatening condition associated with impaired circulation that results in tissue hypoxia. The different types of shock are based on the underlying cause: distributive (↑ cardiac output (CO), ↓ systemic vascular resistance (SVR)), cardiogenic (↓ CO, ↑ SVR), hypovolemic (↓ CO, ↑ SVR), obstructive (↓ CO), and mixed. Types of Shock, ileus, or megacolon Megacolon Megacolon is a severe, abnormal dilatation of the colon, and is classified as acute or chronic. There are many etiologies of megacolon, including neuropathic and dysmotility conditions, severe infections, ischemia, and inflammatory bowel disease. Megacolon).
• Prevention:
  • Infection control:
    • Hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand hygiene
    • Use soap and water rather than alcohol-based hand sanitizer (Clostridioides difficile spores are resistant to alcohol).
  • Minimize antibiotic use.
  • Oral vancomycin prophylaxis for individuals at high risk for CDI

Surgical Site Infections (SSIs)

SSIs

• An infection in the area of a recent surgery 
• 38% of nosocomial infections
• Risk factors:
  • Cigarette smoking
  • Older age
  • Vascular disease
  • Obesity
  • Malnutrition Malnutrition Malnutrition is a clinical state caused by an imbalance or deficiency of calories and/or micronutrients and macronutrients. The 2 main manifestations of acute severe malnutrition are marasmus (total caloric insufficiency) and kwashiorkor (protein malnutrition with characteristic edema). Malnutrition in children in resource-limited countries
  • Diabetes
  • Immunosuppressive therapy
  • Presence of recent or remote infection at the surgical site
  • Recent surgery
  • Hospitalization
  • Transfusion
  • Local wound factors:
    • Edema
    • Proximity to other open or contaminated wound sites
    • Presence of remote infections 
• Microbiology and disease:
  • Common organisms:
    • Skin and mucosal surfaces: gram-positive bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview (e.g., Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus aureus, CoNS).
    • Groin and inguinal areas can be contaminated by gram-negative bacilli and anaerobic organisms. 
  • Infections can be:
    • Superficial (e.g., swelling, warmth, discharge): determined by observation
    • Deeper (e.g., fascia, muscle, or organ involvement): Imaging and exploration are needed.

Management

• Drainage of infected fluid
• Exploration and debridement if necessary (especially in necrotic tissue)
• Antibiotic therapy:
  • Consider the extent of infection, comorbidities, and systemic manifestations.
  • Use for deep infections (not always necessary for superficial infections).
  • Generally guided by culture and sensitivities: Empiric selection is based on initial Gram stain, wound site, and type.
  • The most common organisms to cover:
    • Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus aureus
    • CoNS
    • Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus spp
    • Enterococcus Enterococcus Enterococcus is a genus of oval-shaped gram-positive cocci that are arranged in pairs or short chains. Distinguishing factors include optochin resistance and the presence of pyrrolidonyl arylamidase (PYR) and Lancefield D antigen. Enterococcus is part of the normal flora of the human GI tract. Enterococcus spp 
• Prevention:
  • Patient:
    • Smoking cessation
    • Bowel preparation before colon Colon The large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal. Colon, Cecum, and Appendix surgery
  • Infection control:
    • Hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand hygiene
    • Surgical attire and barrier devices
    • Antimicrobial prophylaxis
    • Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus aureus decolonization
    • Application of antiseptics to the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin
    • Hair removal: Avoid shaving with razors at the planned operative site.
  • Other perioperative measures:
    • Maintain normothermia.
    • Limit people and entry into the operating room.
    • Use of laminar airflow
    • Supplemental oxygen
    • Minimize red cell transfusion.
    • Glucose control
    • Topical and local antibiotic delivery
    • Intraoperative wound protectors
  • Prophylactic negative pressure wound therapy

Clinical Relevance

• Urinary tract infections: a wide spectrum of diseases from simple cystitis (self-limited) to severe pyelonephritis Pyelonephritis Pyelonephritis is infection affecting the renal pelvis and the renal parenchyma. This condition arises mostly as a complication of bladder infection that ascends to the upper urinary tract. Pyelonephritis can be acute or chronic (which results from persistent or chronic infections). Typical acute symptoms are flank pain, fever, and nausea with vomiting. T Pyelonephritis and Perinephric Abscess. Infections are most commonly caused by Escherichia coli Escherichia coli The gram-negative bacterium Escherichia coli is a key component of the human gut microbiota. Most strains of E. coli are avirulent, but occasionally they escape the GI tract, infecting the urinary tract and other sites. Less common strains of E. coli are able to cause disease within the GI tract, most commonly presenting as abdominal pain and diarrhea. Escherichia coli. Features include dysuria, urinary urgency, frequency, suprapubic pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, and fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever. Urinalysis and culture are used to establish the diagnosis. Management is with antibiotics (e.g., trimethoprim-sulfamethoxazole, nitrofurantoin, ceftriaxone). Further workup may be needed if no resolution.
• Pneumonia: infection of the lung parenchyma most commonly caused by a bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview or virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology: Overview. Community-acquired pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia (CAP) accounts for 80% of cases. If the infection is acquired while admitted to a healthcare facility, the infection is termed a healthcare-associated pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia (HCAP). The diagnosis is based on a clinical presentation of fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, productive cough, dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea, rales, and consolidation on chest X-ray. Atypical pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia may present with milder symptoms and less remarkable imaging. Empiric antibiotic treatment is generally appropriate for CAP, while pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia in the ventilated patient often requires culture-based therapy. 
• Sepsis: organ dysfunction resulting from a dysregulated systemic host response to infection. Etiology is mainly bacterial with pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia as the most common source. Patients commonly present with fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, tachycardia, tachypnea, hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension, and/or altered mentation. Septic shock Septic shock Organ dysfunction resulting from a dysregulated systemic host response to infection separates sepsis from uncomplicated infection. Patients commonly present with fever, tachycardia, tachypnea, hypotension, and/or altered mentation. Septic shock is diagnosed during treatment when vasopressors are necessary to control hypotension. Sepsis and Septic Shock is diagnosed during treatment when vasopressors are necessary to control hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension. Sepsis and septic shock Sepsis and Septic shock Organ dysfunction resulting from a dysregulated systemic host response to infection separates sepsis from uncomplicated infection. The etiology is mainly bacterial and pneumonia is the most common known source. Patients commonly present with fever, tachycardia, tachypnea, hypotension, and/or altered mentation. Septic shock is diagnosed during treatment when vasopressors are necessary to control hypotension. Sepsis and septic shock are medical emergencies and antibiotics are given within an hour of diagnosis. Sepsis and Septic Shock are medical emergencies and antibiotics are given within 1 hour of diagnosis.