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Microbiology CT 4 > Listeria and Rhodococcus > Flashcards

Listeria and Rhodococcus Flashcards

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Biology 101 flashcards
1
Q

Microscopical examination of Listeria

A

Gram +
Medium sized rods or coccobacilli
Peritrichous, motile at temp 20-25 degrees C
No flagella at 37 degrees C
Arranged in V form or palisade arrangement

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2
Q

Listeria cultivation properties

A

S (rarely R) form
Aerobe or facultative anaerobic (grow at 10% CO2)
Grow at 3-35 degrees C (wide range of temp and pH)
24 hours

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3
Q

Listeria reaction to catalase and oxidase

A

Catalase +, oxidase -

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4
Q

Diagnostic test for Listeria

A

Hydrolyse aesculine - 10% NaCl

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5
Q

Where can we find Listeria?

A

Saprophytes, present in:
Soil
Plants
Vegetation
Faeces
Silage (pH over 5,5)

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6
Q

Infections of Listeria may result in (3)

A

Septicaemia
Encephalitis
Abortion

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7
Q

Name a food-borne pathogen

A

Listeria monocytogenes.
Found in milk, meat and vegetable, and can multiply at refrigerator temperature!

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8
Q

Name pathogenic species of Listeria

A

Listeria monocytogenes and Listeria ivanovii

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9
Q

Non-pathogenic species of Listeria

A

Listeria innocua and Listeria grayi

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10
Q

What does Listeria monocytogenes cause?

A

Septicaemic listeriosis in young animals
Neural listeriosis (Circling disease) and abortions in sheep, goats and cattle
Iritis in cattle

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11
Q

What does Listeria ivanovii cause?

A

Abortions in sheep and cattle

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12
Q

Virulence factors of Listeria (5)

A

Listeriolyzin O - destroy membranes of phagocytic vacuoles
Phospholipase C
Actin-based motility
Exoenzymes and toxins
Stress protein

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13
Q

How does Listeria invade host cells?

A

Listeria invade both phagocytic and non-phagocytic cells
Survive and replicate intracellularly
Transfer cell-to-cell without exposure to humoral defence mechanisms
Spread via lymph and blood
Have affinity to CNS and placenta

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14
Q

Material for cultivation of Listeria

A

Cerebrospinal fluid, placenta, fetus, liver, blood, spleen, milk, meat

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15
Q

Listeria on meat-peptone-broth

A

Homogenous turbidity

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16
Q

Listeria on meat-peptone-agar

A

S form
Small
Transparent

17
Q

Listeria on blood agar

A

S form
Small
Greyish-white colonies
L. monocytogenes have narrow zone of b-hemolysis
L. ivanovii have wide zone of b-hemolysis

18
Q

CAMP test for Listeria monocytogenes

A

positive with St. aureus

19
Q

CAMP test for Listeria ivanovii

A

positive with rhodococcus equi

20
Q

CAMP test for Listeria innocua

A

Negative

21
Q

Commercial selective and indicator media for Listeria

A

PALCAM medium. Double-indicator system:
1. Aesculin and iron
2. Mannitol and phenol red

22
Q

Listeria monocytogenes reaction with aesculin

A

L. monocytogenes hydrolyses aesculin resulting in black zone around colonies.
Does NOT ferment mannitol - makes it easy to differentiate from contaminants such as mannitol, enterococci and staphylococci.
Medium is changed from red to yellow.

23
Q

Listeria on:
Catalase
Oxidase
Glucose
Mannitol

A

Catalase +
Oxidase -
Glucose +
Mannitol -

24
Q

L. monocytogenes:
rhamnose
xylose

A

rhamnose +
xylose -

25
Q

L. ivanovii:
rhamnose
xylose

A

rhamnose -
xylose +

26
Q

Antigens on Listeria

A

Somatic O and flagellar H

27
Q

Biological test for Listeria

A

Anton’s eye test

28
Q

Describe Anton’s eye test

A

inoculation of the conjunctiva of a rabbit or guinea-pig.
L. monocytogenes causes purulent keratoconjunctivitis in positive case within 24-36 hours.

29
Q

Special examination of Listeria

A

Motility test
Semisolid medium at 22-25 degrees C - umbrella shaped growth.
Phage typing
DNA methods

30
Q

Microscopical examination of rhodococcus

A

Gram + cocci or rods
Capsule +
Non-motile

31
Q

Rhodococcus equi causes (3)

A

Suppurative bronchopneumonia
Lymphadenitis
Abscesses

32
Q

What is EQUI factor?

A

Phospholipase C and cholesterol oxidase, produced by rhodococcus equi

33
Q

CAMP test for rhodococcus equi

A

Positive with St. aureus

34
Q

Rhodococcus equi on blood agar

A

S form
Small
Smooth
No hemolysis
Become larger M form after 48 hours - salmon pink

Microbiology CT 4 (6 decks)

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