Bacillus

Classification

General Characteristics

Basic features of Bacillus spp.

• Gram-positive Gram-Positive Penicillins rods
• Spore Spore The reproductive elements of lower organisms, such as bacteria; fungi; and cryptogamic plants. Microsporidia/Microsporidiosis forming:
  • Endospores (dehydrated cells)
  • Highly resistant to heat Heat Inflammation and other environmental exposures
  • Can persist in soil in a dormant state for many years
• Catalase Catalase An oxidoreductase that catalyzes the conversion of hydrogen peroxide to water and oxygen. It is present in many animal cells. A deficiency of this enzyme results in acatalasia. Nocardia/Nocardiosis positive
• Aerobic

Pathogenic species

• Bacillus anthracis Bacillus anthracis A species of bacteria that causes anthrax in humans and animals. Anthrax (B. anthracis):
  • Colonies show halo projections known as “medusa heads.”
  • Form long chains when grown in culture
  • Grow on blood agar Blood agar Nocardia/Nocardiosis at 37°C (98.6°F), non-hemolytic
  • Have non-functional flagellae (defective flagellin proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis); non-motile
  • Virulence factors Virulence factors Those components of an organism that determine its capacity to cause disease but are not required for its viability per se. Two classes have been characterized: toxins, biological and surface adhesion molecules that affect the ability of the microorganism to invade and colonize a host. Haemophilus:
    • Polypeptide D-glutamate capsule 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. Bacteroides (stains with India ink India ink Cryptococcus/Cryptococcosis)
    • Edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema factor ( EF EF Cardiac Cycle)
    • Lethal factor (LF)
    • Protective antigen Antigen Substances that are recognized by the immune system and induce an immune reaction. Vaccination (PA)
• B. cereus
  • Grow well on blood or chocolate agar Chocolate agar Haemophilus at 25°C–37°C (77°F–98.6°F)
  • Beta-hemolytic
  • Motile, have flagellae
  • Produce 2 types of enterotoxins:
    • Diarrheal toxin ( heat Heat Inflammation labile)
    • Emetic toxin ( heat Heat Inflammation stable)
  • Virulence factors Virulence factors Those components of an organism that determine its capacity to cause disease but are not required for its viability per se. Two classes have been characterized: toxins, biological and surface adhesion molecules that affect the ability of the microorganism to invade and colonize a host. Haemophilus:
    • Phospholipase C Phospholipase C A subclass of phospholipases that hydrolyze the phosphoester bond found in the third position of glycerophospholipids. Although the singular term phospholipase C specifically refers to an enzyme that catalyzes the hydrolysis of phosphatidylcholine, it is commonly used in the literature to refer to broad variety of enzymes that specifically catalyze the hydrolysis of phosphatidylinositols. Pseudomonas regulator (PlcR)
    • Controls expression of hemolysins Hemolysins Proteins from bacteria and fungi that are soluble enough to be secreted to target erythrocytes and insert into the membrane to form beta-barrel pores. Biosynthesis may be regulated by hemolysin factors. Leptospira/Leptospirosis, enterotoxins, phospholipases, and proteases Proteases Proteins and Peptides

B. anthracis

Epidemiology

• Primarily affects animals Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, animalia was one of the kingdoms. Under the modern three domain model, animalia represents one of the many groups in the domain eukaryota. Cell Types: Eukaryotic versus Prokaryotic (herbivores)
• Sheep, cattle, goats, and horses act as a natural reservoir Reservoir Animate or inanimate sources which normally harbor disease-causing organisms and thus serve as potential sources of disease outbreaks. Reservoirs are distinguished from vectors (disease vectors) and carriers, which are agents of disease transmission rather than continuing sources of potential disease outbreaks. Humans may serve both as disease reservoirs and carriers. Escherichia coli.
• Humans usually become infected accidentally through contact with animals Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, animalia was one of the kingdoms. Under the modern three domain model, animalia represents one of the many groups in the domain eukaryota. Cell Types: Eukaryotic versus Prokaryotic or their products.
• Spores Spores The reproductive elements of lower organisms, such as bacteria; fungi; and cryptogamic plants. Anthrax are used as a bioterrorism Bioterrorism The use of biological agents in terrorism. This includes the malevolent use of bacteria; viruses; or other biological toxins against people, animals; or plants. Anthrax agent.
• Some cases were reported secondary to laboratory accidents.

Transmission

• Transcutaneous:
  • Infected animals Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, animalia was one of the kingdoms. Under the modern three domain model, animalia represents one of the many groups in the domain eukaryota. Cell Types: Eukaryotic versus Prokaryotic
  • Animal products
• Ingestion: undercooked meat from animals Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, animalia was one of the kingdoms. Under the modern three domain model, animalia represents one of the many groups in the domain eukaryota. Cell Types: Eukaryotic versus Prokaryotic infected with anthrax Anthrax Anthrax is an infection caused by the bacterium Bacillus anthracis, which usually targets the skin, lungs, or intestines. Anthrax is a zoonotic disease and is usually transmitted to humans from animals or through animal products. Symptoms depend on which organ system is affected. Anthrax
• Spore Spore The reproductive elements of lower organisms, such as bacteria; fungi; and cryptogamic plants. Microsporidia/Microsporidiosis inhalation
• Direct, parenteral injection: rare
• Does NOT occur person to person

Pathogenesis

• PA:
  • Named so because PA serves as the target for the anthrax Anthrax Anthrax is an infection caused by the bacterium Bacillus anthracis, which usually targets the skin, lungs, or intestines. Anthrax is a zoonotic disease and is usually transmitted to humans from animals or through animal products. Symptoms depend on which organ system is affected. Anthrax vaccine Vaccine Suspensions of killed or attenuated microorganisms (bacteria, viruses, fungi, protozoa), antigenic proteins, synthetic constructs, or other bio-molecular derivatives, administered for the prevention, amelioration, or treatment of infectious and other diseases. Vaccination
  • Attaches to host surface proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis
  • Allows toxin entrance into the cytosol Cytosol A cell’s cytoskeleton is a network of intracellular protein fibers that provides structural support, anchors organelles, and aids intra- and extracellular movement. The Cell: Cytosol and Cytoskeleton
• EF EF Cardiac Cycle:
  • Mimics cyclic adenosine Adenosine A nucleoside that is composed of adenine and d-ribose. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter. Class 5 Antiarrhythmic Drugs monophosphate ( 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)
  • Causes characteristic edematous, black eschar in cutaneous anthrax Anthrax Anthrax is an infection caused by the bacterium Bacillus anthracis, which usually targets the skin, lungs, or intestines. Anthrax is a zoonotic disease and is usually transmitted to humans from animals or through animal products. Symptoms depend on which organ system is affected. Anthrax
  • Induces multiorgan hemorrhage
• LF:
  • Exotoxin that acts as a protease Protease Enzyme of the human immunodeficiency virus that is required for post-translational cleavage of gag and gag-pol precursor polyproteins into functional products needed for viral assembly. HIV protease is an aspartic protease encoded by the amino terminus of the pol gene. HIV Infection and AIDS
  • Cleaves mitogen-activated protein (MAP) kinase
  • Causes tissue necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage
• Polypeptide capsule 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. Bacteroides: 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 aversion of phagocytosis Phagocytosis The engulfing and degradation of microorganisms; other cells that are dead, dying, or pathogenic; and foreign particles by phagocytic cells (phagocytes). Innate Immunity: Phagocytes and Antigen Presentation

Clinical presentation

In the United States, 3 clinical manifestations occur.

1. Cutaneous anthrax Anthrax Anthrax is an infection caused by the bacterium Bacillus anthracis, which usually targets the skin, lungs, or intestines. Anthrax is a zoonotic disease and is usually transmitted to humans from animals or through animal products. Symptoms depend on which organ system is affected. Anthrax:
   • Painless papule Papule Elevated lesion < 1 cm in diameter Generalized and Localized Rashes surrounded by vesicles Vesicles Female Genitourinary Examination
   • Black eschar at the site of contact
   • Most common manifestation, self-limited course
   • Rarely, can progress to bacteremia Bacteremia The presence of viable bacteria circulating in the blood. Fever, chills, tachycardia, and tachypnea are common acute manifestations of bacteremia. The majority of cases are seen in already hospitalized patients, most of whom have underlying diseases or procedures which render their bloodstreams susceptible to invasion. Glycopeptides and death
2. Gastrointestinal anthrax Anthrax Anthrax is an infection caused by the bacterium Bacillus anthracis, which usually targets the skin, lungs, or intestines. Anthrax is a zoonotic disease and is usually transmitted to humans from animals or through animal products. Symptoms depend on which organ system is affected. Anthrax:
   • Ulcerative lesion that produces abdominal pain Abdominal Pain Acute Abdomen, vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia, 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
   • Lesion may then perforate.
   • Rare and lethal
3. Pulmonary anthrax Anthrax Anthrax is an infection caused by the bacterium Bacillus anthracis, which usually targets the skin, lungs, or intestines. Anthrax is a zoonotic disease and is usually transmitted to humans from animals or through animal products. Symptoms depend on which organ system is affected. Anthrax (wool-sorter’s disease):
   • Flu-like symptoms Flu-Like Symptoms Babesia/Babesiosis
   • Long incubation Incubation The amount time between exposure to an infectious agent and becoming symptomatic. Rabies Virus initially, up to 60 days
   • Rapid progression to 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, pulmonary hemorrhage, mediastinitis Mediastinitis Mediastinitis refers to an infection or inflammation involving the mediastinum (a region in the thoracic cavity containing the heart, thymus gland, portions of the esophagus, and trachea). Acute mediastinitis can be caused by bacterial infection due to direct contamination, hematogenous or lymphatic spread, or extension of infection from nearby structures. Mediastinitis, and 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
   • Chest X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests: widened mediastinum Widened Mediastinum Imaging of the Mediastinum or pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion
   • Approximately 50% of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship will develop hemorrhagic 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.

Identification Identification Defense Mechanisms

• Cultures showing encapsulated Encapsulated Klebsiella bacilli Bacilli Shigella:
  • Blood
  • Pleural fluid
  • Cerebrospinal fluid Cerebrospinal Fluid A watery fluid that is continuously produced in the choroid plexus and circulates around the surface of the brain; spinal cord; and in the cerebral ventricles. Ventricular System: Anatomy
• Serologic testing during the convalescent period

Management

• Antimicrobials ( 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 and doxycycline)
• Antitoxin (raxibacumab or anthrax Anthrax Anthrax is an infection caused by the bacterium Bacillus anthracis, which usually targets the skin, lungs, or intestines. Anthrax is a zoonotic disease and is usually transmitted to humans from animals or through animal products. Symptoms depend on which organ system is affected. Anthrax immunoglobulin)
• Drainage of pleural effusions
• Supportive care, 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

Prevention

• Primarily through animal vaccination Vaccination Vaccination is the administration of a substance to induce the immune system to develop protection against a disease. Unlike passive immunization, which involves the administration of pre-performed antibodies, active immunization constitutes the administration of a vaccine to stimulate the body to produce its own antibodies. Vaccination
• Human anthrax Anthrax Anthrax is an infection caused by the bacterium Bacillus anthracis, which usually targets the skin, lungs, or intestines. Anthrax is a zoonotic disease and is usually transmitted to humans from animals or through animal products. Symptoms depend on which organ system is affected. Anthrax vaccine Vaccine Suspensions of killed or attenuated microorganisms (bacteria, viruses, fungi, protozoa), antigenic proteins, synthetic constructs, or other bio-molecular derivatives, administered for the prevention, amelioration, or treatment of infectious and other diseases. Vaccination is available for:
  • Certain veterinary, laboratory, or military personnel
  • Post-exposure prophylaxis Prophylaxis Cephalosporins

B. cereus

Epidemiology

• Abundant in soil, fresh and marine water
• Frequent food contaminant
• Normally transiently present in the human gastrointestinal tract (up to 43%)
• B. cereus bacteremia Bacteremia The presence of viable bacteria circulating in the blood. Fever, chills, tachycardia, and tachypnea are common acute manifestations of bacteremia. The majority of cases are seen in already hospitalized patients, most of whom have underlying diseases or procedures which render their bloodstreams susceptible to invasion. Glycopeptides can occur in injection drug users, neonates, immunosuppressed patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship, and patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with prosthetic devices.

Transmission

• Ingestion:
  • Meats
  • Vegetables
  • Reheated rice/grains
• Spores Spores The reproductive elements of lower organisms, such as bacteria; fungi; and cryptogamic plants. Anthrax:
  • Can survive cooking temperatures
  • As food cools, spores Spores The reproductive elements of lower organisms, such as bacteria; fungi; and cryptogamic plants. Anthrax germinate and produce toxins.
• Direct parenteral injection: IV drug users 

Pathogenesis

• Food poisoning Food poisoning Acute illnesses, usually affecting the gastrointestinal tract, brought on by consuming contaminated food or beverages. Most of these diseases are infectious, caused by a variety of bacteria, viruses, or parasites that can be foodborne. Sometimes the diseases are caused by harmful toxins from the microbes or other chemicals present in the food. Especially in the latter case, the condition is often called food poisoning. Clostridia when ingested:
  • Symptoms are related to toxin production.
  • Diarrheal toxin is produced by ingested 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 in vegetative or spore Spore The reproductive elements of lower organisms, such as bacteria; fungi; and cryptogamic plants. Microsporidia/Microsporidiosis forms.
  • Emetic toxin is produced in the food and ingested directly.
• Bacteremia Bacteremia The presence of viable bacteria circulating in the blood. Fever, chills, tachycardia, and tachypnea are common acute manifestations of bacteremia. The majority of cases are seen in already hospitalized patients, most of whom have underlying diseases or procedures which render their bloodstreams susceptible to invasion. Glycopeptides (bloodstream infection) causes various organ seeding Seeding The local implantation of tumor cells by contamination of instruments and surgical equipment during and after surgical resection, resulting in local growth of the cells and tumor formation. Grading, Staging, and Metastasis.
• Soft-tissue 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 can occur in traumatic wounds on direct contact. 

Clinical presentation

• Diarrheal food poisoning Food poisoning Acute illnesses, usually affecting the gastrointestinal tract, brought on by consuming contaminated food or beverages. Most of these diseases are infectious, caused by a variety of bacteria, viruses, or parasites that can be foodborne. Sometimes the diseases are caused by harmful toxins from the microbes or other chemicals present in the food. Especially in the latter case, the condition is often called food poisoning. Clostridia:
  • Occurs 6–14 hours after ingestion
  • Associated with meats and vegetables
  • Symptoms secondary to heat-labile enterotoxin Heat-labile enterotoxin Escherichia coli
  • Watery diarrhea Watery diarrhea Rotavirus and abdominal cramps Cramps Ion Channel Myopathy for a median of 24 hours
• Emetic food poisoning Food poisoning Acute illnesses, usually affecting the gastrointestinal tract, brought on by consuming contaminated food or beverages. Most of these diseases are infectious, caused by a variety of bacteria, viruses, or parasites that can be foodborne. Sometimes the diseases are caused by harmful toxins from the microbes or other chemicals present in the food. Especially in the latter case, the condition is often called food poisoning. Clostridia:
  • Rapid onset, occurs 2–3 hours after ingestion
  • Associated with reheated rice and grains
  • Symptoms secondary to heat-stable enterotoxin Heat-stable enterotoxin Escherichia coli
  • 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 and vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia for a median of 9 hours
  • Remember to differentiate from Staphylococcus aureus Staphylococcus aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Brain Abscess ( S. aureus S. aureus Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications. Staphylococcus) food poisoning Food poisoning Acute illnesses, usually affecting the gastrointestinal tract, brought on by consuming contaminated food or beverages. Most of these diseases are infectious, caused by a variety of bacteria, viruses, or parasites that can be foodborne. Sometimes the diseases are caused by harmful toxins from the microbes or other chemicals present in the food. Especially in the latter case, the condition is often called food poisoning. Clostridia
• Rare manifestations:
  • 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
  • Necrotizing soft tissue Soft Tissue Soft Tissue Abscess 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
  • 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
  • Keratitis Keratitis Inflammation of the cornea. Herpes Simplex Virus 1 and 2: associated with post-cataract surgery or contact lens Lens A transparent, biconvex structure of the eye, enclosed in a capsule and situated behind the iris and in front of the vitreous humor (vitreous body). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the ciliary body is crucial for ocular accommodation. Eye: Anatomy usage

Identification Identification Defense Mechanisms

• Cultures:
  • Stool (for cases of diarrheal poisoning)
  • Blood (if systemic infection suspected)
• Assays to detect diarrheal toxin