Corynebacterium Characteristics
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Questions and Answers

What is the primary mechanism of listeriolysin O in preventing the killing of Listeria monocytogenes by macrophages?

  • It damages the phagosome membrane (correct)
  • It produces superoxide free radicals
  • It inhibits phagocytosis
  • It inhibits the production of catalase

    • What is the specific characteristic of Listeria monocytogenes that allows it to survive in certain conditions?

  • It can survive in the presence of oxygen
  • It can survive in the presence of antibiotics
  • It can survive at refrigerator temperature under conditions of low pH and high salt concentration (correct)
  • It can survive at high temperatures

    • What is the primary purpose of using McBride Medium in the laboratory diagnosis of Listeriosis?

  • To detect the presence of superoxide dismutase
  • To identify the catalase-positive reaction
  • To detect the presence of listeriolysin O
  • To isolate Listeria monocytogenes from polymicrobial clinical specimens (correct)

    • Which of the following is a virulence factor of Listeria monocytogenes?

    <p>Phospholipase C</p> Signup and view all the answers

    What is the primary role of the surface protein p60 in Listeria monocytogenes?

    <p>It induces phagocytosis</p> Signup and view all the answers

    What is the characteristic of Listeria monocytogenes that allows it to be differentiated from other similar bacteria?

    <p>Hippurate hydrolysis positive</p> Signup and view all the answers

    What is the primary group of individuals affected by Listeriosis?

    <p>Neonates, pregnant women, older adults, and immunocompromised hosts</p> Signup and view all the answers

    What is the drug of choice for treating Listeriosis?

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

    What is the temperature at which Listeria monocytogenes grows, allowing for a technique called cold enrichment?

    <p>4°C</p> Signup and view all the answers

    What is the characteristic of Erysipelothrix rhusiopathiae that allows it to form long filaments?

    <p>It is a pleomorphic rod</p> Signup and view all the answers

    What is the typical route of infection for Erysipelothrix rhusiopathiae?

    <p>Through cuts or scratches on the skin</p> Signup and view all the answers

    What is the characteristic of Arcanobacterium haemolyticum colonies on SBA?

    <p>A narrow zone of β-hemolysis</p> Signup and view all the answers

    What is the characteristic of Erysipelothrix rhusiopathiae growth on gelatin stab culture?

    <p>A 'test tube brush-like' pattern at 22°C</p> Signup and view all the answers

    What is the disease caused by Erysipelothrix rhusiopathiae in humans?

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

    What is the characteristic of Trueperella (Arcanobacterium) pyogenes?

    <p>It is an animal pathogen</p> Signup and view all the answers

    What is the characteristic of Arcanobacterium haemolyticum colonies on agar?

    <p>A black opaque dot</p> Signup and view all the answers

    What is the primary concern for healthy individuals, particularly pregnant women, regarding Listeria monocytogenes?

    <p>Spontaneous abortion and stillborn neonates</p> Signup and view all the answers

    What is the characteristic motility of Listeria monocytogenes at room temperature?

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

    What is the optimal growth temperature for Listeria monocytogenes?

    <p>30°C to 35°C</p> Signup and view all the answers

    What is the characteristic arrangement of Listeria monocytogenes cells?

    <p>Singly, in short chains, or in palisades</p> Signup and view all the answers

    What is the characteristic hemolysis of Listeria monocytogenes on blood agar?

    <p>β-hemolysis</p> Signup and view all the answers

    What is the primary laboratory diagnosis method for Listeria monocytogenes?

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

    What is the typical outcome of Listeria monocytogenes infection in newborns?

    <p>Early-onset listeriosis</p> Signup and view all the answers

    What is the preferred carbon dioxide (CO2) level for Listeria monocytogenes growth?

    <p>Slightly increased CO2</p> Signup and view all the answers

    Study Notes

    Corynebacterium

    • Produces coccoid cells
    • Corynebacterium diphtheriae has grayish white colonies
    • Urease positive, differentiating it from Actinomycetes
    • Corynebacterium urealyticum is most commonly associated with UTIs and is lipophilic and a strict aerobe
    • Pinpoint, nonhemolytic, white colonies with characteristic coryneform microscopic morphology
    • Nitrate negative, catalase positive, and urease positive within minutes after inoculation on a Christensen urea slant
    • Drug of choice: vancomycin

    Listeria Monocytogenes

    • Virulence factors: hemolysin (listeriolysin O), catalase, superoxide dismutase, phospholipase C, and surface protein (p60)
    • Can survive at refrigerator temperature under conditions of low pH and high salt concentration
    • Culture media of choice: McBride Medium
    • Infections: primarily affects neonates, pregnant women, older adults, and immunocompromised hosts
    • Clinical infections: Listeriosis, newborns and immunocompromised adults, and pregnant women
    • Spontaneous abortion and stillborn neonates can occur
    • Newborns: early-onset listeriosis (can cause illness shortly after birth) and late-onset listeriosis (disease can occur from several days to two weeks)

    Laboratory Diagnosis

    • Microscopy: Gram-positive coccobacillus, found in singly, in short chains, or in palisades
    • Cultural characteristics: grows well on SBA, chocolate agar, nutrient agars, brain-heart infusion medium, and thioglycolate broth
    • Prefers a slightly increased carbon dioxide (CO2) and optimal growth temperature: 30°C to 35°C
    • Colonies are small, round, smooth, and translucent, surrounded by a narrow zone of β-hemolysis
    • Cold enrichment may be used to isolate the organism from polymicrobial clinical specimens
    • Identification: hippurate hydrolysis positive, catalase positive, bile esculin hydrolysis positive, and motile at room temperature
    • Wet mount preparations: “tumbling motility” (end-over-end motility) and produces a positive CAMP reaction

    Erysipelothrix Rhusiopathiae

    • General characteristics: three species in the genus Erysipelothrix, gram positive, catalase negative, non-spore-forming, and pleomorphic rod
    • Usual route of infection is through cuts or scratches on skin, commensal pathogen on vertebrates and invertebrates
    • Only species in this genus that can cause disease in humans, causing localized skin disease (Erysipeloid)

    Arcanobacterium and Trueperella

    • General characteristics: catalase negative, nonmotile, pleomorphic, aerobic or facultatively anaerobic
    • Arcanobacterium haemolyticum (formerly Corynebacterium haemolyticum) and Trueperella (Arcanobacterium) pyogenes are associated with causing infections in humans
    • Trueperella pyogenes is an animal pathogen, best known for causing infections in cattle
    • Small colonies on SBA with narrow zone of β-hemolysis after 24 to 48 hours of incubation
    • A black opaque dot is observed on the agar when the colony is scraped away

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    Description

    This quiz covers the characteristics of Corynebacterium, a genus of bacteria, including its morphology, growth, and enzymatic activities. Learn about the different species of Corynebacterium and their distinct features.

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