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 Escape With constant immune mechanisms holding unstable tumor cells in equilibrium, tumor-cell variants may emerge. These cancer cells may express fewer antigens on their surfaces or lose their MHC class I expression.Variants may also protect themselves from T-cell attack via expression of IC molecules on their surfaces, like normal cells.Creation of an immunosuppressive state in the microenvironment is another way to grow without immunologic interference. Cancer Immunotherapy the GI tract, infecting 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: Anatomy and other sites. Less common strains of E. coli are able to cause disease within the GI tract, most commonly presenting as abdominal pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways 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. E. coli is transmitted via a fecal–oral route, which can occur with unsanitary food preparation, contamination of meat or produce by manure, irrigating or washing crops/fruits with contaminated water, and consumption of contaminated water.

Last updated: Sep 8, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Classification

Gram negative bacteria classification flowchart

Gram-negative bacteria gram-negative bacteria Bacteria which lose crystal violet stain but are stained pink when treated by gram’s method. Bacteriology:
Most 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 can be classified according to a lab procedure called Gram staining Gram staining Bacteriology.
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 with cell walls that have a thin layer of peptidoglycan Peptidoglycan Penicillins do not retain the crystal violet stain utilized in Gram staining Gram staining Bacteriology. These 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 do, however, retain the safranin counterstain and thus appear as pinkish-red on the stain, making them gram negative Gram negative Bacteria which lose crystal violet stain but are stained pink when treated by gram’s method. Yersinia spp./Yersiniosis. These 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 can be further classified according to morphology (diplococci, curved rods, bacilli Bacilli Shigella, and coccobacilli) and their ability to grow in the presence of oxygen (aerobic versus anaerobic). The 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 can be more narrowly identified by growing them on specific media (triple sugar iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements ( TSI TSI Shigella) agar) where their 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 can be identified ( urease Urease An enzyme that catalyzes the conversion of urea and water to carbon dioxide and ammonia. Nocardia/Nocardiosis, oxidase Oxidase Neisseria) and their ability to ferment lactose can be tested.
* Stains poorly on Gram stain Gram stain Klebsiella
** Pleomorphic Pleomorphic Bacteroides rod/coccobacillus
*** Require special transport media

Image by Lecturio.

General Characteristics

  • Features:
    • Stain: gram-negative
    • Morphology: bacillus Bacillus Bacillus are aerobic, spore-forming, gram-positive bacilli. Two pathogenic species are Bacillus anthracis (B. anthracis) and B. cereus. Bacillus (rod)
    • Facultative anaerobic
    • Either nonmotile or motile (flagellated)
    • Catalase-positive
    • Ferments lactose 
  • Special media and biochemical test:
Photomicrograph of escherichia coli

Photomicrograph of Escherichia coli

Image: “E. coli 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” by NIAID. License: CC BY 2.0

Pathogenesis and Virulence Factors

Virulence Virulence The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its virulence factors. Proteus

  • Antigenic structures:
    • O antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination: component of the lipopolysaccharide Lipopolysaccharide Lipid-containing polysaccharides which are endotoxins and important group-specific antigens. They are often derived from the cell wall of gram-negative bacteria and induce immunoglobulin secretion. The lipopolysaccharide molecule consists of three parts: lipid a, core polysaccharide, and o-specific chains (o antigens). When derived from Escherichia coli, lipopolysaccharides serve as polyclonal b-cell mitogens commonly used in laboratory immunology. Klebsiella (LPS) in the cell wall Cell wall The outermost layer of a cell in most plants; bacteria; fungi; and algae. The cell wall is usually a rigid structure that lies external to the cell membrane, and provides a protective barrier against physical or chemical agents. Cell Types: Eukaryotic versus Prokaryotic
    • H antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination: flagellar protein
    • K antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination: polysaccharide capsule Polysaccharide capsule An envelope of loose gel surrounding a bacterial cell which is associated with the virulence of pathogenic bacteria. Some capsules have a well-defined border, whereas others form a slime layer that trails off into the medium. Most capsules consist of relatively simple polysaccharides but there are some bacteria whose capsules are made of polypeptides. Klebsiella 
  • Adherence factors and toxins are specific to the E. coli strain.

Avirulent variants of Escherichia coli

  • Reservoir:
    • Humans are the primary reservoir.
    • Strains are part of the normal gut flora.
  • Transmission:
    • In 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: Anatomy infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease (UTIs):
      • Bacterium ascends urethra Urethra A tube that transports urine from the urinary bladder to the outside of the body in both the sexes. It also has a reproductive function in the male by providing a passage for sperm. Urinary Tract: Anatomy to cause infection. 
      • More common in women or with catheter use
      • Type 1 Type 1 Spinal Muscular Atrophy fimbriae ( pili Pili Filamentous or elongated proteinaceous structures which extend from the cell surface in gram-negative bacteria that contain certain types of conjugative plasmid. These pili are the organs associated with genetic transfer and have essential roles in conjugation. Normally, only one or a few pili occur on a given donor cell. This preferred use of ‘pili’ refers to the sexual appendage, to be distinguished from bacterial fimbriae, also known as common pili, which are usually concerned with adhesion. Salmonella): virulence Virulence The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its virulence factors. Proteus factor that allows bacterial attachment to uroepithelial cells.
    • In neonatal meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis:
      • Infant infected with maternal E. coli through rupture of membranes or during childbirth
      • K1 capsular polysaccharide: virulence Virulence The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its virulence factors. Proteus factor in most cases

Pathogenic variants of Escherichia coli

  • Pathogenic strains are found exogenously and are introduced through unsanitary food production or preparation.
  • Transmission:
    • Fecal–oral route
    • Contaminated meat or produce
  • Employ various virulence Virulence The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its virulence factors. Proteus factors in producing illness, depending on the pathogen
Table: Pathogenic variants of E. coli
Pathogen Pathogenesis/ Virulence Virulence The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its virulence factors. Proteus factor Signs and Symptoms
ETEC
  • Fimbrial adhesins Adhesins Cell-surface components or appendages of bacteria that facilitate adhesion (bacterial adhesion) to other cells or to inanimate surfaces. Most fimbriae of gram-negative bacteria function as adhesins, but in many cases it is a minor subunit protein at the tip of the fimbriae that is the actual adhesin. In gram-positive bacteria, a protein or polysaccharide surface layer serves as the specific adhesin. What is sometimes called polymeric adhesin (biofilms) is distinct from protein adhesin. Diarrheagenic E. coli allow binding to the intestinal mucosa Intestinal Mucosa Lining of the intestines, consisting of an inner epithelium, a middle lamina propria, and an outer muscularis mucosae. In the small intestine, the mucosa is characterized by a series of folds and abundance of absorptive cells (enterocytes) with microvilli. Small Intestine: Anatomy
  • Heat-labile (LT) enterotoxin Enterotoxin Substances that are toxic to the intestinal tract causing vomiting, diarrhea, etc. ; most common enterotoxins are produced by bacteria. Diarrhea increases cAMP cAMP An adenine nucleotide containing one phosphate group which is esterified to both the 3′- and 5′-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and acth. Phosphodiesterase Inhibitors → altered electrolyte transport (↑ chloride Chloride Inorganic compounds derived from hydrochloric acid that contain the Cl- ion. Electrolytes secretion Secretion Coagulation Studies) 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
  • LT: related to cholera toxin Cholera toxin An enterotoxin from Vibrio cholerae. It consists of two major protomers, the heavy (h) or a subunit and the B protomer which consists of 5 light (l) or B subunits. The catalytic a subunit is proteolytically cleaved into fragments a1 and a2. The a1 fragment is a mono(adp-ribose) transferase. The B protomer binds cholera toxin to intestinal epithelial cells, and facilitates the uptake of the a1 fragment. The a1 catalyzed transfer of adp-ribose to the alpha subunits of heterotrimeric g proteins activates the production of cyclic amp. Increased levels of cyclic amp are thought to modulate release of fluid and electrolytes from intestinal crypt cells. Vibrio
  • Heat-stabile (ST) enterotoxin Enterotoxin Substances that are toxic to the intestinal tract causing vomiting, diarrhea, etc. ; most common enterotoxins are produced by bacteria. Diarrhea increases cGMP cGMP Guanosine cyclic 3. Phosphodiesterase Inhibitors 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
  • No 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 or invasion
No 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 or invasion → traveler’s 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 (watery)
EPEC
  • For colonization Colonization Bacteriology, requires bundle-forming pilus (BFP) (encoded by a plasmid EPEC adherence factor or EAF)
  • Carries chromosomal locus Locus Specific regions that are mapped within a genome. Genetic loci are usually identified with a shorthand notation that indicates the chromosome number and the position of a specific band along the P or Q arm of the chromosome where they are found. For example the locus 6p21 is found within band 21 of the P-arm of chromosome 6. Many well known genetic loci are also known by common names that are associated with a genetic function or hereditary disease. Basic Terms of Genetics of enterocyte effacement (LEE), which encodes intimin, a specific adhesin that binds intestinal epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology
  • No toxin production
Mild 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 → 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 with mucus
EAEC
  • Aggregative adherence fimbriae (AAF) to adhere to intestinal mucosa Intestinal Mucosa Lining of the intestines, consisting of an inner epithelium, a middle lamina propria, and an outer muscularis mucosae. In the small intestine, the mucosa is characterized by a series of folds and abundance of absorptive cells (enterocytes) with microvilli. Small Intestine: Anatomy; forms a biofilm Biofilm Encrustations formed from microbes (bacteria, algae, fungi, plankton, or protozoa) embedded in an extracellular polymeric substance matrix that is secreted by the microbes. They occur on body surfaces such as teeth (dental deposits); inanimate objects, and bodies of water. Biofilms are prevented from forming by treating surfaces with dentifrices; disinfectants; anti-infective agents; and anti-fouling agents. Staphylococcus
  • “Stacked-brick” adherence pattern
  • Some possess a heat-stable (ST) enterotoxin Enterotoxin Substances that are toxic to the intestinal tract causing vomiting, diarrhea, etc. ; most common enterotoxins are produced by bacteria. Diarrhea, similar to ETEC.
Mild 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 → 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
EHEC
  • Binds to intestinal epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology via bacterial fimbriae
  • Employs phage-encoded Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli:
    • Cytotoxic Cytotoxic Parvovirus B19 to both intestinal villi and 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: Anatomy epithelial cells
    • Inhibits protein synthesis Synthesis Polymerase Chain Reaction (PCR) cell death Cell death Injurious stimuli trigger the process of cellular adaptation, whereby cells respond to withstand the harmful changes in their environment. Overwhelmed adaptive mechanisms lead to cell injury. Mild stimuli produce reversible injury. If the stimulus is severe or persistent, injury becomes irreversible. Apoptosis is programmed cell death, a mechanism with both physiologic and pathologic effects. Cell Injury and Death
  • O157:H7 strain may lead to hemolytic uremic syndrome Hemolytic uremic syndrome A syndrome that is associated with microvascular diseases of the kidney, such as renal cortical necrosis. It is characterized by hemolytic anemia; thrombocytopenia; and acute renal failure. Hypocoagulable Conditions.
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 dysentery Dysentery Acute inflammation of the intestine associated with infectious diarrhea of various etiologies, generally acquired by eating contaminated food containing toxins, biological derived from bacteria or other microorganisms. Dysentery is characterized initially by watery feces then by bloody mucoid stools. It is often associated with abdominal pain; fever; and dehydration. Gastroenteritis (bloody 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)
EIEC Direct invasion of the intestinal epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology and formation of enterotoxins → necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage and 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 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 dysentery Dysentery Acute inflammation of the intestine associated with infectious diarrhea of various etiologies, generally acquired by eating contaminated food containing toxins, biological derived from bacteria or other microorganisms. Dysentery is characterized initially by watery feces then by bloody mucoid stools. It is often associated with abdominal pain; fever; and dehydration. Gastroenteritis (bloody 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) similar to Shigella Shigella Shigella is a genus of gram-negative, non-lactose-fermenting facultative intracellular bacilli. Infection spreads most commonly via person-to-person contact or through contaminated food and water. Humans are the only known reservoir. Shigella
ETEC = enterotoxigenic E. coli
EPEC = enteropathogenic E. coli
EAEC = enteroaggregative E. coli
EHEC = enterohemorrhagic E. coli
EIEC = enteroinvasive E. coli

Associated Diseases

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: Anatomy infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease

  • E. coli is the leading cause of UTIs in women.
  • Diagnosis: urinalysis Urinalysis Examination of urine by chemical, physical, or microscopic means. Routine urinalysis usually includes performing chemical screening tests, determining specific gravity, observing any unusual color or odor, screening for bacteriuria, and examining the sediment microscopically. Urinary Tract Infections (UTIs) in Children with urine culture Urine culture Urinary tract infections (UTIs)
  • Treatment: antibiotics (e.g., nitrofurantoin, trimethoprim–sulfamethoxazole Trimethoprim–sulfamethoxazole A drug combination with broad-spectrum antibacterial activity against both gram-positive and gram-negative organisms. It is effective in the treatment of many infections, including pneumocystis pneumonia in aids. Chronic Granulomatous Disease)

Neonatal meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis

  • E. coli can cause meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis and sepsis Sepsis Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock. Sepsis and Septic Shock (which often coexist, or sepsis Sepsis Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock. Sepsis and Septic Shock may precede meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis).
  • Signs and symptoms:
    • 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
    • Full fontanelles Fontanelles Physical Examination of the Newborn
    • Vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia
    • Coma Coma Coma is defined as a deep state of unarousable unresponsiveness, characterized by a score of 3 points on the GCS. A comatose state can be caused by a multitude of conditions, making the precise epidemiology and prognosis of coma difficult to determine. Coma
    • Convulsions Convulsions Seizures
    • Poor or absent Moro reflex Moro Reflex Primitive Reflexes
    • Hypertonia Hypertonia Abnormal increase in skeletal or smooth muscle tone. Skeletal muscle hypertonicity may be associated with pyramidal tract lesions or basal ganglia diseases. Neurological Examination or hypotonia Hypotonia Duchenne Muscular Dystrophy
  • Diagnosis: CSF analysis CSF analysis Meningitis showing leukocytosis Leukocytosis A transient increase in the number of leukocytes in a body fluid. West Nile Virus and low glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance and 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 on Gram stain Gram stain Klebsiella
  • Treatment: antibiotics (e.g., ceftriaxone Ceftriaxone A broad-spectrum cephalosporin antibiotic and cefotaxime derivative with a very long half-life and high penetrability to meninges, eyes and inner ears. Cephalosporins)

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

  • Enterotoxigenic E. coli (ETEC):
    • Most common cause of traveler’s 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 worldwide
    • 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 usually in resource-limited settings (especially with sanitation Sanitation The development and establishment of environmental conditions favorable to the health of the public. Hepatitis E Virus problems)
    • Short incubation Incubation The amount time between exposure to an infectious agent and becoming symptomatic. Rabies Virus period, lasting ≤ 5 days
    • Watery, secretory 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, with nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics, cramping:
      • Similar to cholera Cholera An acute diarrheal disease endemic in india and southeast Asia whose causative agent is Vibrio cholerae. This condition can lead to severe dehydration in a matter of hours unless quickly treated. Vibrio
      • 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 from ETEC is rice-colored.
      • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship can lose up to 20 L of fluid a day.
    • Diagnosis: detection of heat-labile or heat-stable enterotoxins (by polymerase chain reaction Polymerase chain reaction Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR) ( PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR)))
    • Treatment is supportive.
  • Enteropathogenic E. coli (EPEC):
    • EPEC is a major cause of sporadic Sporadic Selective IgA Deficiency 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 in children (mostly < 2 years of age) in developing countries.
    • 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 without blood nor pus
    • Diagnosis: stool PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR)
    • Treatment is supportive.
  • Enteroaggregative E. coli (EAEC):
    • EAEC is the second most common cause of traveler’s 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.
    • Results in both acute and chronic 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 in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with HIV HIV Anti-HIV Drugs and AIDS AIDS Chronic HIV infection and depletion of CD4 cells eventually results in acquired immunodeficiency syndrome (AIDS), which can be diagnosed by the presence of certain opportunistic diseases called AIDS-defining conditions. These conditions include a wide spectrum of bacterial, viral, fungal, and parasitic infections as well as several malignancies and generalized conditions. HIV Infection and AIDS 
    • Treatment: 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 to prevent chronic infection
  • Enterohemorrhagic E. coli (EHEC):
    • Primarily a food-borne infection
    • Painful, bloody 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
    • Infection with strain O157:H7 can lead to hemolytic uremic syndrome Hemolytic uremic syndrome A syndrome that is associated with microvascular diseases of the kidney, such as renal cortical necrosis. It is characterized by hemolytic anemia; thrombocytopenia; and acute renal failure. Hypocoagulable Conditions ( HUS HUS Hemolytic uremic syndrome (HUS) is a clinical phenomenon most commonly seen in children that consists of a classic triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Hemolytic uremic syndrome is a major cause of acute kidney injury in children and is most commonly associated with a prodrome of diarrheal illness caused by shiga-like toxin-producing bacteria. Hemolytic Uremic Syndrome), a triad of:
      • Hemolytic 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 and Types
      • Thrombocytopenia Thrombocytopenia Thrombocytopenia occurs when the platelet count is < 150,000 per microliter. The normal range for platelets is usually 150,000-450,000/µL of whole blood. Thrombocytopenia can be a result of decreased production, increased destruction, or splenic sequestration of platelets. Patients are often asymptomatic until platelet counts are < 50,000/µL. Thrombocytopenia
      • AKI AKI Acute kidney injury refers to sudden and often reversible loss of renal function, which develops over days or weeks. Azotemia refers to elevated levels of nitrogen-containing substances in the blood that accompany AKI, which include BUN and creatinine. Acute Kidney Injury
    • Children are more likely to develop HUS HUS Hemolytic uremic syndrome (HUS) is a clinical phenomenon most commonly seen in children that consists of a classic triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Hemolytic uremic syndrome is a major cause of acute kidney injury in children and is most commonly associated with a prodrome of diarrheal illness caused by shiga-like toxin-producing bacteria. Hemolytic Uremic Syndrome than adults.
    • Diagnosis: detection of Shiga toxin Shiga toxin A class of toxins that inhibit protein synthesis by blocking the interaction of ribosomal RNA; with peptide elongation factors. They include shiga toxin which is produced by Shigella dysenteriae and a variety of shiga-like toxins that are produced by pathologic strains of Escherichia coli such as Escherichia coli o157. Diarrheagenic E. coli by enzyme immunoassay Enzyme immunoassay HIV Infection and AIDS or PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR)
    • Treatment:
      • Supportive
      • Avoid antibiotics, as they have been associated with the development of HUS HUS Hemolytic uremic syndrome (HUS) is a clinical phenomenon most commonly seen in children that consists of a classic triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Hemolytic uremic syndrome is a major cause of acute kidney injury in children and is most commonly associated with a prodrome of diarrheal illness caused by shiga-like toxin-producing bacteria. Hemolytic Uremic Syndrome.
  • Enteroinvasive E. coli (EIEC):
    • Seen in travelers to and children in developing countries 
    • EIEC directly invades the intestinal epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium: Histology, causing bloody 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.
    • Treatment is supportive.

References

  1. Holtz, L. R., Tarr, P. I. (2021). Shiga toxin-producing Escherichia coli: clinical manifestations, diagnosis, and treatment. UpToDate. Retrieved April 26, 2021, from https://www.uptodate.com/contents/shiga-toxin-producing-escherichia-coli-clinical-manifestations-diagnosis-and-treatment
  2. Johnson, J. R. (1991). Virulence factors in Escherichia coli urinary tract infection. Clinical Microbiology Reviews 4:80–128. https://pubmed.ncbi.nlm.nih.gov/1672263/
  3. Nataro, J. P., Calderwood, S. B. (2020). Pathogenic Escherichia coli associated with diarrhea. UpToDate. Retrieved April 26, 2021, from https://www.uptodate.com/contents/pathogenic-escherichia-coli-associated-with-diarrhea
  4. Nguyen, Y., Sperandio, V. (2012). Enterohemorrhagic E. coli (EHEC) pathogenesis. Frontiers in Cellular and Infection Microbiology 12:90. https://pubmed.ncbi.nlm.nih.gov/22919681/
  5. Ryan, K. J. (Ed.). (2017). Sherris Medical Microbiology, 7th ed. McGraw-Hill. https://accessmedicine.mhmedical.com/content.aspx?bookid=2268&sectionid=176087050
  6. Sarowska, J., Futoma-Koloch, B., Jama-Kmiecik, A., et al. (2019). Virulence factors, prevalence and potential transmission of extraintestinal pathogenic Escherichia coli isolated from different sources: recent reports. Gut Pathogens 11(10). https://doi.org/10.1186/s13099-019-0290-0 
  7. Steffen, R. (2005). Epidemiology of traveler’s diarrhea. Clinical Infectious Diseases 41:536–540. https://pubmed.ncbi.nlm.nih.gov/16267715/

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