Bacteriology exam prep: Rhodococcus, Trueperella, Bacillus
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Questions and Answers

What is the pH range in which Rhodococcus hoagii multiplies in herbivore manure and large intestines of foals?

  • 7.5-8.5
  • 6.5-7.5
  • 8.5-10 (correct)
  • 5.5-6.5

    • What is the primary source of infection for Rhodococcus hoagii in foals?

  • Vector transmission
  • Contact with infected foals
  • Ingestion of contaminated soil
  • Inhalation of airborne particles (correct)

    • What is the result of Rhodococcus hoagii interfering with phagosome maturation in macrophages?

  • Formation of acidic vacuoles
  • Formation of pH-neutral vacuoles (correct)
  • Activation of immune responses
  • Cell-mediated immunity

    • What is the characteristic of Rhodococcus hoagii that allows it to replicate inside macrophages?

    <p>Facultative intracellular</p> Signup and view all the answers

    What is the typical age range of foals that develop severe symptoms of Rhodococcus hoagii infection?

    <p>4-12 weeks</p> Signup and view all the answers

    Which of the following is NOT a common manifestation of Rhodococcus hoagii infection in horses?

    <p>Tuberculosis</p> Signup and view all the answers

    What is the primary population affected by Rhodococcus hoagii infection in humans?

    <p>Immunocompromised populations</p> Signup and view all the answers

    Which of the following animals is NOT commonly affected by Rhodococcus hoagii infection?

    <p>Fish</p> Signup and view all the answers

    What is the morphology of Rhodococcus hoagii?

    <p>Morphologically irregular coccoid to rod-shaped</p> Signup and view all the answers

    What is the characteristic of Rhodococcus hoagii that allows it to survive in macrophages?

    <p>Coprophilic</p> Signup and view all the answers

    Which species of Trueperella is often associated with pathogenic synergy with Fusobacterium necrophorum?

    <p>T. pyogenes</p> Signup and view all the answers

    What type of infections are commonly caused by Trueperella pyogenes?

    <p>Purulent infections</p> Signup and view all the answers

    Which is NOT a target tissue or organ for Trueperella pyogenes infections?

    <p>Pancreas</p> Signup and view all the answers

    Which of the following best describes the metabolism type of Trueperella species?

    <p>Aerobic and facultative anaerobe</p> Signup and view all the answers

    What is the significance of T. pyogenes producing lactic acid in its pathogenic synergy with F. necrophorum?

    <p>It supplies energy for F. necrophorum</p> Signup and view all the answers

    Which characteristic is NOT associated with Trueperella species?

    <p>Motile</p> Signup and view all the answers

    How are Trueperella pyogenes infections in cattle commonly initiated?

    <p>Endogenously, often through traumatic or opportunistic origins</p> Signup and view all the answers

    Which of the following commensal bacteria often complicate local infections caused by T. pyogenes?

    <p>Non-spore forming anaerobes such as Bacteriodes and Fusobacterium</p> Signup and view all the answers

    Which of the following animals are most commonly affected by Trueperella pyogenes infections?

    <p>Pigs and cattle</p> Signup and view all the answers

    Which method of transmission is primarily responsible for mastitis in cattle caused by Trueperella?

    <p>Cow-to-cow transmission, mediated by flies</p> Signup and view all the answers

    What primarily disrupts the protective epithelium of the endometrium in dairy cattle, making them susceptible to T. pyogenes infections?

    <p>Parturition</p> Signup and view all the answers

    Which microorganism does T. pyogenes synergistically interact with to cause liver abscesses in feedlot cattle?

    <p>Fusobacterium necrophorum</p> Signup and view all the answers

    What condition in cattle leads to the opportunistic invasion of T. pyogenes through the damaged epithelium of the rumen?

    <p>Ruminal acidosis</p> Signup and view all the answers

    Which condition is most likely poly-microbial involving T. pyogenes, among other organisms?

    <p>Liver abscesses</p> Signup and view all the answers

    What type of severe infection does T. pyogenes cause in dairy cows that leads to purulent secretions following an injury?

    <p>Mastitis</p> Signup and view all the answers

    Which factor is NOT directly associated with the spread of mastitis in cattle herds?

    <p>Grass diet</p> Signup and view all the answers

    Which small ruminant species is commonly affected by T. pyogenes causing abscesses in different tissues?

    <p>Sheep</p> Signup and view all the answers

    Which type of cellular activity of T. pyogenes contributes to inflammatory lesions in the endometrium of cattle?

    <p>Cytolytic activity</p> Signup and view all the answers

    What is the percentage range of hepatic abscess occurrence attributed to T. pyogenes in feedlot cattle?

    <p>2-25%</p> Signup and view all the answers

    Which condition in pigs is NOT typically associated with T. pyogenes infection?

    <p>Foot abscesses</p> Signup and view all the answers

    What is the primary way that spores of Bacillus anthracis enter the host?

    <p>All of the above</p> Signup and view all the answers

    What is the primary virulence factor of Bacillus anthracis that disables the host's immune system?

    <p>Lethal factor (LEF)</p> Signup and view all the answers

    What is the name of the form of Bacillus anthracis that is found in the environment?

    <p>Spore</p> Signup and view all the answers

    What are the first symptoms of anthrax in ruminants?

    <p>Sudden and unexpected death</p> Signup and view all the answers

    What is the name of the disease caused by Bacillus anthracis?

    <p>Anthrax</p> Signup and view all the answers

    What is the primary way that Bacillus anthracis spores survive in the environment?

    <p>In alkaline soils</p> Signup and view all the answers

    What is the name of the toxin produced by Bacillus anthracis?

    <p>Anthrax toxin</p> Signup and view all the answers

    What is the primary way that Bacillus anthracis spores are transmitted?

    <p>Through direct contact</p> Signup and view all the answers

    What is the name of the form of anthrax that occurs when Bacillus anthracis spores enter the body through a skin wound?

    <p>Cutaneous anthrax</p> Signup and view all the answers

    What is the primary virulence factor of Bacillus anthracis that helps it evade the host's immune system?

    <p>Capsule</p> Signup and view all the answers

    What is the primary mechanism by which Rhodococcus hoagii evades the host's immune response?

    <p>Ability to replicate inside macrophages and inhibit phagosome maturation</p> Signup and view all the answers

    Which of the following is a common manifestation of Rhodococcus hoagii infection in foals?

    <p>Ulcerative typhlocolitis and mesenteric lymphadenitis</p> Signup and view all the answers

    What is the primary mode of transmission of Trueperella pyogenes in cattle?

    <p>Indirect contact through contaminated environment</p> Signup and view all the answers

    Which of the following tissues is NOT a common target for Trueperella pyogenes infections?

    <p>Skeletal muscles</p> Signup and view all the answers

    What is the role of Trueperella pyogenes in the pathogenesis of liver abscesses in feedlot cattle?

    <p>Synergistic interaction with Fusobacterium necrophorum to cause abscesses</p> Signup and view all the answers

    Which of the following conditions is NOT typically associated with Trueperella pyogenes infections in cattle?

    <p>Pneumonia</p> Signup and view all the answers

    What is the primary mechanism by which Trueperella pyogenes causes disease in cattle?

    <p>Direct invasion of tissues and induction of inflammatory responses</p> Signup and view all the answers

    Which of the following is a common complication of Trueperella pyogenes infections in cattle?

    <p>Secondary bacterial infections</p> Signup and view all the answers

    What is the primary factor that contributes to the development of mastitis in dairy cattle?

    <p>Disruption of the protective epithelium of the endometrium</p> Signup and view all the answers

    Which of the following is a common manifestation of Trueperella pyogenes infections in swine?

    <p>Abscesses in various tissues</p> Signup and view all the answers

    Which Bacillus species is an obligate pathogen known to cause disease in animals and humans?

    <p>B.anthracis</p> Signup and view all the answers

    What characteristic is common among most Bacillus species?

    <p>Endospore production</p> Signup and view all the answers

    Under which environmental condition are anthrax outbreaks most commonly observed?

    <p>Neutral to alkaline calcareous soils with soil disturbance</p> Signup and view all the answers

    Which virulence factor of Bacillus anthracis is essential for binding to host cells and transporting toxins?

    <p>Protective antigen</p> Signup and view all the answers

    Which group of Bacillus species includes the opportunistic pathogen B.cereus?

    <p>B.cereus group</p> Signup and view all the answers

    What term describes most Bacillus species' ability to grow best at moderate temperatures?

    <p>Mesophilic</p> Signup and view all the answers

    Which environmental condition does not typically support the dormancy of Bacillus spores?

    <p>Flooded soils</p> Signup and view all the answers

    What key component of Edema Factor (EF) disrupts water homeostasis in host cells?

    <p>Conversion of ATP to cAMP</p> Signup and view all the answers

    How does a high concentration of cAMP, generated by Edema Factor (EF), affect host cells?

    <p>Results in water efflux</p> Signup and view all the answers

    Which virulence factor is specifically responsible for providing strong antiphagocytic protection to Bacillus anthracis?

    <p>Capsule</p> Signup and view all the answers

    Which form of anthrax is characterized by localized edema and necrotic lesions with a coal-black appearance?

    <p>Cutaneous anthrax</p> Signup and view all the answers

    What is the primary function of peptidases in the pathogenesis of Bacillus anthracis?

    <p>Metabolizing peptides in mammalian hosts</p> Signup and view all the answers

    What is the role of haemolysins in Bacillus anthracis virulence?

    <p>Acquiring iron</p> Signup and view all the answers

    What mechanism is primarily associated with the inactivation of phagocytes by Edema Factor (EF)?

    <p>Conversion of ATP to cAMP</p> Signup and view all the answers

    Which virulence factor primarily contributes to the induction of necrosis in host cells?

    <p>Lethal Factor (LEF)</p> Signup and view all the answers

    What is the primary characteristic of the acute form of anthrax in pigs?

    <p>Progressive swelling of the throat</p> Signup and view all the answers

    What is the primary method of preventing the spread of anthrax?

    <p>Safe disposal and destruction of infected carcasses</p> Signup and view all the answers

    What is the primary effect of oxygen on anthrax spores?

    <p>It leads to rapid sporulation</p> Signup and view all the answers

    What is the primary reason antibiotics are not typically recommended for treating anthrax?

    <p>There is a risk of antibiotic resistance</p> Signup and view all the answers

    What is the primary difference between the acute and chronic forms of anthrax in pigs?

    <p>The acute form is characterized by oropharyngitis, while the chronic form is characterized by non-specific signs</p> Signup and view all the answers

    What is the primary effect of intensive surveillance on animals in contact with infected animals?

    <p>It leads to early detection and treatment of infected animals</p> Signup and view all the answers

    What is the primary reason for burying or destroying infected carcasses?

    <p>To prevent the spread of the disease</p> Signup and view all the answers

    What is the primary characteristic of Bacillus cereus infections in dogs and cats?

    <p>They are characterized by food poisoning</p> Signup and view all the answers

    What is the primary effect of vaccination on anthrax?

    <p>It reduces the severity of symptoms but does not provide complete protection</p> Signup and view all the answers

    What is the primary difference between the symptoms of anthrax in horses and pigs?

    <p>Horses typically exhibit different symptoms, such as fever and chills, while pigs exhibit symptoms such as oropharyngitis</p> Signup and view all the answers

    Which form of anthrax is commonly associated with hemorrhagic lymphadenitis leading to pulmonary lymphatic obstruction?

    <p>Pulmonary anthrax</p> Signup and view all the answers

    What is the primary mode of transmission for intestinal anthrax?

    <p>Ingestion of infected meat</p> Signup and view all the answers

    In which type of environment is pulmonary anthrax most frequently seen in ruminants?

    <p>Dry prairies with short grass</p> Signup and view all the answers

    What clinical signs in cattle may raise a strong suspicion of anthrax?

    <p>Rapid raise of body temperature, staggering, dyspnea</p> Signup and view all the answers

    What is a potential outcome of the immune response to intestinal anthrax infections?

    <p>Massive effusion and mucosal edema</p> Signup and view all the answers

    Which variant of intestinal anthrax is known to cause inflammatory lesions in the oral cavity?

    <p>Oropharyngeal variant</p> Signup and view all the answers

    What condition in pulmonary anthrax might lead to obstructive edema and death in ruminants?

    <p>Pulmonary lymphatic obstruction</p> Signup and view all the answers

    Which of the following correctly describes septicemia caused by anthrax in humans or animals?

    <p>Widespread infection leading to multiple organ failure</p> Signup and view all the answers

    What is a common clinical feature of anthrax in animals before sudden death occurs?

    <p>Minor anorexia and reduction in milk yield</p> Signup and view all the answers

    Study Notes

    Genus Rhodococcus

    • Widespread, environmental bacterium found in soil, particularly in fecally contaminated farm environments
    • Rhodococcus hoagii (equi) is the only recognized animal pathogen, causing diseases in horses and humans

    Characteristics of Rhodococcus hoagii

    • Gram +’ve
    • Obligate aerobic
    • Non-motile
    • Non-spore forming
    • Morphologically irregular coccoid to rod shaped
    • Facultative intracellular
    • Can proliferate inside macrophages
    • Coprophilic
    • Multiplies in basic pH (8.5-10) herbivore manure and large intestines of foals

    Transmission of Rhodococcus hoagii

    • Inhalation of airborne particles, particularly in summers when contaminated soil comes desiccated
    • Ingestion
    • Infected foal's breath may also be a source of infection in advanced cases of pneumonia

    Pathogenesis of Rhodococcus hoagii

    • Uptake of bacteria into local macrophages at portal of entry
    • Alveolar macrophages in the lungs
    • Bacteria interferes with phagosome maturation creating a pH neutral vacuole
    • Bacterial survival and replication inside pH-neutral vacuole
    • Accumulation of replicate bacteria in the macrophage leads to cytotoxicity
    • Cell necrosis
    • Cascade of proinflammatory signals released, destroying tissues and forming abscesses

    Foal Rhodococcosis

    • Multifocal purulent bronchopneumonia with abscessation in foals that do not have effective cell-mediated immune response
    • Very rarely seen in adult horses
    • Exposure to the bacteria soon after birth leads to a gradual development of infection
    • Subtle until severe symptoms develop between 4-12 weeks of age
    • Other less common manifestations found outside the lungs, spread from primary lesions that are in the lungs or intestines

    Other Manifestations

    • Osteomyelitis
    • Purulent arthritis
    • Ulcerative lymphangitis
    • Reactive arthritis and ocular inflammatory processes
    • Ulcerative typhlocolitis and Mesenteric Lymphadenitis
    • Seen in 50% of foals with rhodococcal pneumonia

    Rhodococcosis in Other Animals

    • Swine and Cattle: Pyogranulomatous lesions in the submandibular, bronchial, and mediastinal lymph nodes, often confused with tuberculosis at slaughter
    • Form severe systemic caseating abscesses in the lungs, liver, and other organs in goats and camelids
    • Humans: Affects primarily immunocompromised populations, presenting as subacute pneumonia
    • Rarely seen in dogs and cats, but associated with immunocompromised patients if reported

    Genus Trueperella

    • Commensal in skin, respiratory, urogenital, and gastrointestinal tracts of production animals, including cattle, swine, domestic, and some companion animals.
    • Opportunistic pathogen that can cause pyogenic infections, including mastitis, arthritis, pneumonia, and abscesses.

    Characteristics

    • Gram-positive
    • Non-motile
    • Non-spore forming
    • Β haemolytic
    • Aerobic and facultative anaerobe
    • Coccobacilli with varying shapes and sizes (short rods to coccobacilli)
    • Can arrange in singles, pairs, or clusters

    Transmission and Infections

    • Endogenous infections
    • Exogenous transmission via cow-to-cow contact, mediated by flies (e.g., mastitis)
    • Often causes infections in combination with other bacteria (e.g., Fusobacterium, Bacteroides, Dichelobactor)
    • Local, regional, or metastatic purulent infections in various tissues and organs (e.g., lungs, pericardium, peritoneum, brain, pleura, endocardium, renal cortex, bones, joints, liver, uterus, subcutaneous tissues)

    Infections in Cattle

    • Metritis and endometritis: T. pyogenes is normal vaginal flora in dairy cattle, opportunistically invading the uterus after parturition and causing infections
    • Liver abscesses in feedlot cattle: T. pyogenes normally found in ruminal wall, opportunistically invading through damaged epithelium with F. necrophorum
    • Foot rot in feedlot and dairy cattle: necrotic infections of the laminae in the hoof, involving T. pyogenes, F. necrophorum, and P. levii
    • Mastitis: severe mastitis with purulent secretions following teat or udder injury, lesions, and dysfunction of the mammary gland

    Infections in Other Species

    • Pigs: abscesses, pneumonia, pleuritis, endocarditis, osteoarthritis, polyarthritis, mastitis, metritis, septicemia
    • Sheep and goats: abscesses in different organs and tissues, including foot abscesses
    • Humans: sporadic, zoonotic infections
    • Horses, dogs, and cats: rare infections caused by T. pyogenes

    Genus Bacillus

    • Most species are saprophytes found in air, soil, and water.
    • Spores can survive in many habitats and are resistant to heat, radiation, disinfection, and desiccation.
    • Can remain dormant in soil for decades.

    Subgroups of Bacillus

    • Divided into three main groups: B. subtilis, B. cereus, and B. circulans.
    • B. subtilis group includes B. subtilis, B. licheniformis, B. pumilis, and B. amyloliquefaciens.
    • B. cereus group includes B. anthracis, B. cereus, B. mycoides, and B. thuringiensis.
    • B. circulans group includes B. circulans, B. firmus, B. coagulans, and B. lentus.

    Characteristics of Bacillus

    • Gram-positive.
    • Large rods.
    • Mostly mesophilic.
    • Aerobic or facultatively anaerobic.
    • Motile.
    • Some exceptions.
    • Endospore-producing.

    Bacillus Anthracis

    • Causes anthrax, which has been reported on nearly every continent, especially in agricultural regions.
    • Spores survive in areas with neutral or alkaline calcareous soils.
    • Epizootic events are associated with droughts, floods, or natural events that cause soil disturbance and stir up spores.
    • Vegetative form is only found in the host body, not in the environment.
    • Only spores are found in the environment.

    Main Virulence Factors of B. Anthracis

    • Toxins:
      • Two toxins encoded in the pXO1 plasmid.
      • Lethal factor (LEF) induces excessive release of cytokines, apoptosis, hypoxia, and cell necrosis.
      • Edema factor (EF) is a highly efficient adenylyl cyclase that converts ATP to cyclic adenosine monophosphate (cAMP).
      • cAMP results in upset water homeostasis in the host cells, leading to massive edema.
      • High concentrations of cAMP result in water efflux.
      • Inactivates phagocytes.
    • Capsule:
      • Encoded by the pXO2 plasmid.
      • Plays a central role in virulence by providing strong antiphagocytic protection.
      • Shields the surface structures from the host immune mechanisms.

    Secondary Virulence Factors

    • B. anthracis is specialized in growing in mammalian hosts and metabolizing peptides, lipids by using peptidases and phospholipases.
    • Iron-acquiring peptides and haemolysins serve as secondary virulence factors.

    B. Anthracis Transmission and Pathogenesis

    • Spores enter the host by skin breach, ingestion, or inhalation.
    • Can cause three forms of anthrax:
      • Cutaneous anthrax:
        • Low-level germination at the site of infection.
        • Growth leads to localized edema and necrotic lesions of the skin.
        • Lesions have a coal-black appearance.
        • Rarely described in animals, but if it is, it's usually in pigs.
        • Rarely results in septicemia.

    Intestinal Anthrax

    • Largely underreported in humans and animals, with immune responses ranging from subclinical infections to death
    • Usually acquired through ingestion of infected meat
    • Characterized by low-level germination at the site of infection, leading to massive effusion, mucosal edema, and necrotic lesion formation

    Intestinal Anthrax Symptoms

    • Can present as an oropharyngeal variant, causing fever, toxemia, and inflammatory lesions in the oral cavity
    • Enlargement of cervical lymph nodes and edema of the cervical soft tissue are also common symptoms

    Pulmonary Anthrax

    • The most severe and frequent form in ruminants, associated with herds farmed on dry prairies with short grass where spores are easily inhaled
    • Inhaled spores lead to rapid spread into regional lymph nodes, development of hemorrhagic lymphadenitis, septicemia, toxemia, and shock, ultimately resulting in death

    Anthrax in Ruminants

    • Sudden and unexpected death, possibly preceded by minor anorexia and reduction in milk yield
    • Cattle may experience a rapid raise of body temperature (~41.5ºC), staggering, dyspnea, trembling, collapse with convulsive movements, and bleeding from the orifices just before or at the time of death

    Anthrax in Other Species

    Horses

    • Acute, with death typically occurring in 2-3 days following symptom onset
    • Symptoms include fever, chills, severe colic, anorexia, depression, weakness, diarrhea, swelling of neck, swelling of abdomen and sternum, and swelling of external genitalia

    Pigs

    • More resistant to anthrax, but may develop into septicemia
    • Acute form characterized by oropharyngitis, progressive swelling of throat, which may result in death by suffocation
    • Chronic form characterized by non-specific signs that get better with treatment, including anorexia, vomiting, diarrhea or constipation

    Dogs, Cats & Wild Carnivores

    • Similar presentation to pigs, but quite resistant to anthrax

    Control & Prevention of Anthrax

    • Safe disposal and destruction of infected carcasses, with burying or carcasses or infect materials forbidden in several countries
    • Culling and burning preferred, with intensive surveillance of animals in contact with infected animals and environment
    • Bacteriological diagnosis via blood sample, avoiding opening carcasses to prevent environmental persistence
    • Vaccinations are available for prophylactic and proactive action

    Other Bacillus Caused Diseases

    Bacillus cereus

    • Causes rare mastitis in cattle, food poisoning in dogs and cats, and food-borne diarrheal illness in humans

    Bacillus licheniformis

    • Causes abortion and mastitis in cattle and sheep, and food-borne diarrheal illness in humans

    Bacillus subtilis

    • Causes ovine abortion, bovine mastitis, and food-borne diarrheal illness in humans

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