Bacteriology: Corynebacterium and Bacillus Species
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Questions and Answers

Which organism is associated with producing the diphtheria toxin?

  • Corynebacterium diphtheriae (correct)
  • Klebs Loeffler’s Bacillus
  • Staphylococcus aureus
  • Bacillus cereus

    • What is the primary mode of transmission for the organism responsible for diphtheria?

  • Airborne transmission
  • Foodborne transmission
  • Person to person exposure (correct)
  • Vector-borne transmission

    • Which of the following characteristics describes Bacillus cereus?

  • Causes fried rice poisoning. (correct)
  • Commonly found in the human nasopharynx.
  • Produces beta-lactamase.
  • Is strictly anaerobic.

    • What is a notable resistance feature of Bacillus cereus spores?

    <p>Resist pasteurization.</p> Signup and view all the answers

    Which of the following symptoms is nonspecific for infections caused by Corynebacterium diphtheriae?

    <p>Low-grade fever</p> Signup and view all the answers

    Which Corynebacterium species is most commonly associated with prosthetic joint infections?

    <p>C. jeikeium</p> Signup and view all the answers

    What type of infection is C. urealyticum primarily associated with?

    <p>Urinary tract infection</p> Signup and view all the answers

    Which Corynebacterium species is known to produce a diphtheria-like toxin?

    <p>C. ulcerans</p> Signup and view all the answers

    Which test is associated with the identification of Corynebacterium species?

    <p>Methylene blue stain</p> Signup and view all the answers

    What is a common consequence of C. pseudotuberculosis infection in humans?

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

    Which Corynebacterium species is part of the normal flora of the skin?

    <p>C. xerosis</p> Signup and view all the answers

    C. jeikeium is primarily associated with which type of infections?

    <p>Hospital-acquired infections</p> Signup and view all the answers

    C. ulcerans is most commonly associated with infections in which animal?

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

    What are common symptoms associated with respiratory diphtheria?

    <p>Respiratory obstruction and cough</p> Signup and view all the answers

    Which two drugs are typically used in the treatment of infections caused by diphtheria?

    <p>Penicillin and Erythromycin</p> Signup and view all the answers

    Which of the following accurately describes the cutaneous form of diphtheria?

    <p>Involves nonhealing skin ulcers</p> Signup and view all the answers

    What is the primary site of infection for acute diphtheria?

    <p>Tonsils and pharynx</p> Signup and view all the answers

    How long is the typical incubation period for the diarrhea-causing form of food poisoning mentioned?

    <p>8-16 hours</p> Signup and view all the answers

    Which of the following forms of food poisoning typically results in more vomiting?

    <p>Emetic food poisoning</p> Signup and view all the answers

    What characteristic is used in the laboratory diagnosis of diphtheria?

    <p>Presence of Babes-Ernst granules</p> Signup and view all the answers

    Which type of complications are considered less common in the context of food poisoning?

    <p>Systemic complications</p> Signup and view all the answers

    What is the Gram stain result typically seen in diphtheria infections?

    <p>Gram-positive pleomorphic bacilli</p> Signup and view all the answers

    What is the most serious potential outcome associated with untreated respiratory diphtheria?

    <p>Cardiac failure</p> Signup and view all the answers

    What is the appearance of Nocardia species on Sabouraud's Dextrose Agar?

    <p>Bumpy, velvety, yellow-orange colonies</p> Signup and view all the answers

    Which type of infection is primarily caused by Nocardia brasiliensis?

    <p>Chronic granulomatous infection of the skin</p> Signup and view all the answers

    What characteristic allows Nocardia to be identified under the microscope?

    <p>Filamentous branching and partially acid-fast properties</p> Signup and view all the answers

    Which culture conditions are necessary for growing Nocardia species?

    <p>Common nonselective medium at 22C to 37C</p> Signup and view all the answers

    What is the treatment of choice for Nocardia infections due to its resistance profile?

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

    Which of the following is a common clinical manifestation of Nocardia asteroides complex?

    <p>Chronic, confluent bronchopneumonia</p> Signup and view all the answers

    Which of the following statements about the Gram stain characteristics of Nocardia is true?

    <p>Nocardia can be mistaken for Gram-positive cocci</p> Signup and view all the answers

    What is a significant culturing challenge for Nocardia species?

    <p>They require extended incubation periods.</p> Signup and view all the answers

    Which feature is true for Bacillus species?

    <p>They can be motile.</p> Signup and view all the answers

    What is the causative agent of cutaneous anthrax?

    <p>Bacillus anthracis</p> Signup and view all the answers

    Which statement about Corynebacterium diphtheriae is accurate?

    <p>It appears as a club-shaped organism.</p> Signup and view all the answers

    What laboratory method can be used to identify Bacillus anthracis?

    <p>Direct Fluorescent Antibody Assay</p> Signup and view all the answers

    Which symptom is most commonly associated with inhalational anthrax?

    <p>Severe respiratory distress</p> Signup and view all the answers

    What type of bacteria are classified as catalase positive, non-branched, and non-spore forming?

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

    Which virulence factor does Bacillus anthracis possess?

    <p>Glutamic acid capsule</p> Signup and view all the answers

    What causes injectional anthrax?

    <p>Direct injection of spores into tissues</p> Signup and view all the answers

    What type of colony morphology is typically observed with Bacillus anthracis?

    <p>Non-hemolytic, gray, and raised colonies</p> Signup and view all the answers

    What is a common transmission route for gastrointestinal anthrax?

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

    Which of the following correctly describes the Gram stain characteristics of Bacillus species?

    <p>Gram-positive bacilli with square ends</p> Signup and view all the answers

    Which species is characterized by a 'medusa head' colony morphology?

    <p>Bacillus anthracis</p> Signup and view all the answers

    What type of bacteria is Nocardia classified as?

    <p>Catalase positive filamentous bacteria</p> Signup and view all the answers

    What is the appearance of Corynebacterium under microscopy?

    <p>Pleomorphic with club shapes</p> Signup and view all the answers

    What is the main virulence factor associated with Listeria monocytogenes?

    <p>Listeriolysin O</p> Signup and view all the answers

    What specific symptom may a pregnant woman experience due to Listeriosis?

    <p>Flu-like illness</p> Signup and view all the answers

    Which laboratory method is primarily used to confirm the toxigenicity of Corynebacterium diphtheriae?

    <p>Elek Test</p> Signup and view all the answers

    What is a key characteristic of Erysipelothrix rhusiopathiae?

    <p>Catalase negative</p> Signup and view all the answers

    Which clinical infection is associated with Erysipelothrix rhusiopathiae?

    <p>Localized skin infection</p> Signup and view all the answers

    In which condition might you find a beta-hemolytic pattern in bacterial culture?

    <p>Group B Streptococcus infection</p> Signup and view all the answers

    Which laboratory culture medium is used for isolating Erysipelothrix rhusiopathiae?

    <p>BAP and CAP</p> Signup and view all the answers

    What is the method of transmission for Listeria monocytogenes?

    <p>Ingestion of contaminated food</p> Signup and view all the answers

    What distinguishes Actinomycetes from other bacterial groups?

    <p>Branching or partially acid-fast features</p> Signup and view all the answers

    Which bacterial species is associated with Whipple disease?

    <p>Tropheryma whipplei</p> Signup and view all the answers

    What is the characteristic morphology of Listeria monocytogenes under the microscope?

    <p>Coccobacilli in clusters</p> Signup and view all the answers

    What type of motility is observed in Listeria monocytogenes?

    <p>Tumbling motility</p> Signup and view all the answers

    What clinical presentation is likely in a newborn infected with Listeria monocytogenes?

    <p>Meningitis and sepsis</p> Signup and view all the answers

    What is the characteristic growth pattern of Erysipelothrix rhusiopathiae in culture?

    <p>Inverted Christmas tree pattern</p> Signup and view all the answers

    Study Notes

    Aerobic Gram-Positive Bacilli

    • Bacillus:

      • Gram-positive: A type of bacteria characterized by its cell wall structure retaining the crystal violet stain in a Gram stain.
      • Aerobic: Requiring oxygen for growth.
      • Spore-forming: Able to produce resilient spores, resistant to adverse conditions.
      • Examples: Bacillus anthracis (anthrax), Bacillus cereus (food poisoning).
      • Methods of Diagnosis: Blood, lung tissue, cerebrospinal fluid (CSF) specimens. Nonhemolytic colonies with gray color and raised structure are visible. Microscopically, the spores appear at the center of the cell, square-ended. Gram staining yields a positive result.

    • Corynebacterium:

      • Gram-positive: A type of bacteria retaining the crystal violet stain in Gram staining.
      • Non-spore forming: Doesn't produce spores.
      • Catalase-positive: Produces the enzyme catalase.
      • Examples: Corynebacterium diphtheriae (diphtheria).
      • Clinical presentation: A sore throat, low-grade fever, malaise. If severe, respiratory distress can arise. Leading to potential complications such as respiratory obstruction and damage to heart, kidneys, and peripheral nerves.
      • Other strains: Appear in varied shapes, including club-shaped and Chinese character patterns.

    • Listeria monocytogenes:

      • Gram-positive: Bacteria appearing as coccobacilli or in chains. Retain the crystal violet stain in Gram staining.
      • Catalase-positive: The presence of catalase enzyme is determined.
      • Non-spore forming: Doesn't produce resilient spores.
      • Motile: Exhibit motility.
      • Clinical infection: Most typically occurs by ingestion of contaminated meat or poultry. Leads to Listeriosis.
      • Susceptibility: Pregnant, immunocompromised individuals, and neonates at increased risk.
      • Symptoms: Flu-like illness, spontaneous abortion, stillbirth in pregnant individuals, meningitis, sepsis in neonates, and central nervous system infection among immunocompromised patients

    • Erysipelothrix rhusiopathiae:

      • Gram-positive: The cell wall structure retains the crystal violet stain in a Gram stain.
      • Non-spore forming: Doesn't produce spores.
      • Catalase-negative: Absence of catalase activity (the enzyme catalase)
      • Clinical presentation: Characterized by localized skin infections. These infections are associated with cuts, scratches, and skin abrasions, in scenarios such as handling meat, poultry, and fish.
      • Diagnosis: Tissue biopsy or aspirate of skin lesions. Appearance of thin, V-shaped gram-positive bacilli are evident in microscopic examination. Growing cultures on blood agar plates or nutrient broth are useful, along with observing the presence of catalase negative cultures and checking for the absence of nitrate and VP reactions.

    • Actinomycetes/Nocardia:

      • Gram-positive: The cell wall structure retains the crystal violet stain in a Gram stain, though some strains demonstrate variable staining qualities.
      • Branching: Characterized by a branching filamentous structure.
      • Partially acid-fast: Exhibit a partial ability to retain a red stain when treated with acid, differing from completely acid-fast bacteria like Mycobacterium.
      • Clinical presentation: Associated with pulmonary and cutaneous infections; may lead to chronic infections in lungs, and skin that are often chronic and granulomatous.
      • Identification: Utilizing nonselective growth mediums at temperatures ranging from 22C to 37C. They are commonly observed in soil and water, causing infections in humans.

    Food Poisoning

    • Bacillus cereus: A possible cause of food poisoning and a common cause of diarrhea or vomiting.

    Additional Information

    • String of pearls: A characteristic morphology of Corynebacterium species.
    • Medusa head colonies: A descriptive visual for Bacillus anthracis cultures.
    • Catalase test: An important diagnostic tool confirming the presence of the catalase enzyme in bacteria.

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    MT 6320 Clinical Bacteriology PDF

    Description

    Test your knowledge on the characteristics and infections associated with Corynebacterium and Bacillus species. This quiz covers topics including diphtheria toxin production, transmission modes, and specific species-related infections. Perfect for students and professionals in microbiology and infectious diseases.

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