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MTAP FIRST SEM 2024-2025 > LISTERIA, CORYNEBACTERIUM, AND SIMILAR ORGANISMS > Flashcards

LISTERIA, CORYNEBACTERIUM, AND SIMILAR ORGANISMS Flashcards

1
Q

General Characteristics
* Catalase-positive
* Gram-positive rods
* Non-acid fast
* Non-spore-forming
* Mostly nonbranching rods

A

LISTERIA, CORYNEBACTERIUM, AND SIMILAR ORGANISMS

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2
Q

CHARACTERISTICS NI Listeria monocytogenes

A
  • Widely distributed in nature and occasionally colonizes the human GIT
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3
Q

HABITAT NI Listeria monocytogenes

A
  • Colonizer: animals, soil,
    and vegetable matter; widespread in
    these environments
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4
Q

MODE OF TRANSMISSION NI Listeria monocytogenes

A
  • Direct contact: human GIT, ingestion of contaminated food (meat and dairy products)
  • Endogenous strain: colonized mothers may pass organism to fetus. Portal of entry is probably from GIT to blood and in some instances from blood and meninges
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5
Q
  • Major virulence factor
  • Pore-forming toxin that reduced T-cell responsiveness
A

Listeriolysin O

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6
Q
  • Bacterial surface protein
  • Induces host cell actin polymerization
A

Act A

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7
Q

What are some localized infections caused by Listeriosis?

A

Stillbirth and neonatal death, meningitis, bacteremia, encephalitis, and endocarditis.

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8
Q

What type of gastroenteritis is associated with Listeriosis?

A

Febrile gastroenteritis is associated with foodborne outbreaks of Listeriosis.

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9
Q

What are some localized infections caused by Listeriosis?

A

conjunctivitis, skin infections, and lymphadenitis.

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10
Q

Characteristics ni Corynebacterium diphtheriae

A
  • Only carried by humans
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11
Q

Habitat ni Corynebacterium diphtheriae

A
  • Colonizer: human nasopharynx but only
    in carrier state; not considered part of the
    normal microbiota
  • Isolation from healthy humans is not
    common
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12
Q

MODE OF TRANSMISSION ni Corynebacterium diphtheriae

A

Primary mode of transmission: respiratory secretions or exudates from skin lesions

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13
Q

extremely potent and lethal, blocking protein synthesis in human cells, causing the cells to die.

A

cytotoxic exotoxin

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14
Q

What are the symptoms of respiratory diphtheria?

A

pharyngitis, dysphagia, low-grade fever, cervical and submandibular lymphadenopathy, fever, general malaise, and headache.

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15
Q

What causes cutaneous diphtheria and what are its symptoms?

A

-toxigenic or nontoxigenic strains
-shallow, chronic skin lesions.

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16
Q

CHARACTERISTICS OF Corynebacterium
jeikeium

A
  • Commonly encountered in clinical
    specimens
  • Not considered highly virulent
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17
Q

HABITAT NI Corynebacterium jeikeium

A
  • Colonizer: skin microbiota of hospitalized
    patients, most commonly on the inguinal, axillary, and rectal sites
18
Q

MODE OF TRANSMISSION Corynebacterium
jeikeium

A
  • Uncertain
  • Direct contact: may be person to
    person
  • Endogenous strains: selection
    during antimicrobial therapy, introduction during placement or improper care of IV catheters
19
Q

s a nosocomial pathogen that causes cystitis in hospitalized patients, especially those who have undergone urologic manipulation and the elderly.

A

C. urealyticum

20
Q

Name two other nosocomial pathogens besides C. urealyticum.

A

C. amycolatum and C. striatum.

21
Q

known as “red coccus,” is isolated worldwide from water, soil, and manure of herbivores.

A

Rhodococcus

22
Q

is used for processing specimens of L. monocytogenes from placenta and other tissues.

A

Cold enrichment

23
Q

What is the primary direct detection method for Listeriosis?

A

Gram staining.

24
Q

How do Listeria monocytogenes appear under a Gram stain?

A

short, gram-positive rods that may occur singly or in short chains resembling streptococci.

25
Q

What media are used for cultivating Corynebacterium spp.?

A

Corynebacterium spp. are cultivated on 5% sheep blood and chocolate agar.

26
Q

What selective media are used for C. diphtheriae?

A

Cystine-tellurite blood agar
Modified Tinsdale agar (TIN)

26
Q

What is the purpose of cystine in the selective media for C. diphtheriae?

A

enhances the growth of fastidious organisms, including C. diphtheriae.

27
Q

How is C. diphtheriae presumptively identified on Tinsdale agar?

A

brown-black colonies with a gray-brown halo on Tinsdale agar

28
Q

How is C. diphtheriae presumptively identified on cystine-tellurite blood agar?

A

black or gray

29
Q

contains serum and egg, stimulates the growth of C. diphtheriae and the production of metachromatic granules in the cells

A

Loeffler’s medium

30
Q

How do colonies of C. diphtheriae appear on Leoffler’s medium?

A

Colonies of C. diphtheriae appear gray to white and translucent within 12-18 hours.

31
Q

What molecular methods are used to identify C. diphtheriae?

A

Ribotyping, pulse-field gel electrophoresis, and multilocus sequence typing.

32
Q

What tests can separate C. diphtheriae from other corynebacterial?

A

Halo in Tinsdale agar and urea hydrolysis.

33
Q

Name some toxin detection methods for C. diphtheriae

A

-Guinea pig lethality test
-immunodiffusion test (Elek Test)
-tissue culture cells
-enzyme immunoassays
-PCR to detect the toxin gene.

34
Q

How is Listeria monocytogenes presumptively identified?

A

By motility using a direct wet mount showing end-over-end tumbling motility, and an umbrella-shaped pattern after overnight incubation at room temperature in semisolid agar.

35
Q

What biochemical tests are positive for Listeria monocytogenes?

A

-Ferments glucose,
-Vogue’s-Proskauer positive,
-esculin positive,
-CAMP positive.

36
Q

What serodiagnosis method is used for Listeriosis?

A

Detection of anti-listeriolysin O antibodies (IgG).

37
Q

How is diphtheria prevented?

A

Through immunization with a multidose diphtheria toxoid prepared by inactivation of the toxin with formaldehyde.

38
Q

What is the treatment for diphtheria?

A

Diphtheria antitoxin (DAT) and either a single dose of IM penicillin or 14 days of erythromycin for symptomatic individuals.

39
Q

What are some preventive measures for listeriosis?

A

-Properly washing raw vegetables and meat,

-immunocompromised and pregnant individuals avoiding soft cheeses, and thoroughly heating

-leftovers or ready-to-eat foods like hotdogs or cold cuts before consumption.

MTAP FIRST SEM 2024-2025 (15 decks)

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