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Clinical Bacteriology Lab > Fastidious Gram-Negative Bacilli > Flashcards

Fastidious Gram-Negative Bacilli Flashcards

1
Q

members of fastidious gram neg bacilli group (hacek)

A
  • haemophilus spp
  • aggregatibacter actinomycetemcomitans
  • cardiobacterium hominis
  • eikenella corrodens
    -kingella spp
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2
Q

fastidious, non motile, capnophilic, and facultatively anaerobic bacteria

A

haemophilus

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3
Q

haemophilus cannot grow on ____

A

pure blood agars

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4
Q

haemophilus is both ____ and ____ positive

A

catalase and oxidase positive

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5
Q

haemophilus is both catalase and oxidase positive except for

A

haemophilus segnis

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6
Q

haemophilus growth factors

A

X and V factors, porphyrin

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7
Q

x factor include

A

hemin

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8
Q

V factors include

A

nicotinamide, adenine dinucleotide or NAD

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9
Q

Haemophilus spp. that are V factor dependent do not grow on ___

A

SBA

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10
Q

Clinical laboratories use __ for the recovery of Haemophilus

A

chocolate (CHOC) agar

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11
Q

A phenomenon that helps in the recognition of
Haemophilus spp. that require V factor is?

A

satellitism

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12
Q

a strictly human pathogen, is the causative agent
of chancroid, a highly communicable sexually transmitted genital ulcer disease (GUD).

A

H. Ducreyi

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13
Q

for h.ducreyi _____ should be used to collect
material from the base of the ulcer.

A

Swab premoistened with sterile phosphate buffered saline

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14
Q

___ on selective media at the bedside is preferred instead of using transport media.

A

Direct plating

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15
Q

Are susceptible to drying

A

Haemophilus spp.

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16
Q

.When attempting to isolate H. influenzae, CHOC agar is a commonly used medium incubated between __ and ___

A

33° and 37°

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17
Q

When attempting to isolate H. influenzae, CHOC agar is a commonly used medium in an atmosphere of

A

5% to 10% carbon dioxide (CO2)

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18
Q

It has been shown that CHOC agar supplemented with _____ is an excellent medium for the isolation of Haemophilus spp. from respiratory specimens.

A

Bacitracin (300mg/L)

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19
Q

for heamophilus spp growth on CHOC agar is usually seen after ___ of incubation

A

18 to 24hours

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20
Q

H. ducreyi also grows on enriched CHOC medium, or a ____ can be used.

A

Nairobi biplate

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21
Q

The use of ___ (most H. ducreyi are resistant) in the media helps reduce the growth of commensal biota from genital specimens and improves the detection of H. ducreyi.

A

Vancomycin

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22
Q

H. ducreyi grows best at

A

33° C.

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23
Q

H. influenzae on CHOC agar appear

A

Tannish

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24
Q

Haemophilus spp. sometimes grow on SBA plates around colonies of other bacterial species— a phenomenon known as

A

Satellitism

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25
Q

An organism is identified as haemophilus influenzae
Because it requires?

A

both X and V factors.

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26
Q

This organism requires V factor only and is identified as

A

Haemophilus parainfluenzae.

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27
Q

The ___ is an alternative method for differentiating the heme-producing species of Haemophilus

A

porphyrin test

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28
Q

has been associated with meningitis.

A

C. hominis

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29
Q

The organisms tend to form rosettes, swellings, long filaments, or sticklike structures in yeast extract.

A

Cardiobacterium hominis

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30
Q

Gram-stained smear of Cardiobacterium hominis showing typical ___

A

Rosettes

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31
Q

They tend to resist decolorization on Gram stain

A

Kingella

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32
Q

require increased CO, for growth and isolation from blood cultures.

A

Capnocytophaga spp.

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33
Q

Capnocytophaga spp. are thin and often - resembling

A

Fusiform ( pointed ends)

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34
Q

produce gliding motility on solid surfaces.

A

Capnocytophaga

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35
Q

On agar Capnocytophaga colonies are often adherent and produce a ___ pigment; they can resemble colonies of E. corrodens.

A

Yellow- orange pigment

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36
Q

. ferment sucrose, glucose, maltose, and lactose, although triple sugar iron agar (TSIA) may be negative without enrichment.

A

Capnocytophaga spp

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37
Q

are gram-negative, nonmotile, facultative anaerobic coccobacilli that appear ovoid, filamentous, or as bacilli.

A

pasteurella spp

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38
Q

safety pin appearance when the poles of the cells are more intensely stained

A

Pasteurella spp. bipolar staining

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39
Q

These bacteria are catalase and oxidase positive and ferment glucose with weak to moderate acid production without gas.

A

Pasteurella spp.

40
Q

All Pasteurella spp. grow on __ and __ agar, producing gravish colonies

A

SBA and CHOC agar

41
Q

does not support the growth of most Pasteurella spp.

A

MAC agar

42
Q

small gram-negative, aerobic, nonmotile,
unencapsulated bacteria that may appear as coccobacilli or bacilli

A

Brucellae

43
Q

Brucellae colonies

A

smooth raised, and translucent colonies

44
Q

Brucellae are facultative intracellular pathogens that can reside within

A

mononuclear phagocytic cells.

45
Q

can vary in their requirement for CO,. They grow on SBA and CHOC agar and can be isolated on MTM or Martin-Lewis media from contaminated specimens.

A

Brucella spp.

46
Q

Brucellae are oxidase and catalase positive and are - urease positive within

A

2 hours

47
Q

Because of the aerosol mode of transmission, Brucella spp should be handled under

A

biosafety level 3 conditions

48
Q

small, nonmotile, gram-negative bacilli or coccoid bacteria and are strictly aerobic.

A

Francisella spp.

49
Q

fastidious and require supplementation with cysteine, cystine, or thiosulfate for growth on successive passage.

A

Francisella spp.

50
Q

F. tularensis are negative in what test

A

oxidase, urease, and satellite or X and V test

51
Q

F. Tularensis is weakly positive for

A

Catalase and beta-lactamase

52
Q

A presumptive identification for brucella can be made by a positive test result in any one of the following assays:

A
  • Direct fluorescent antibody (DNA)
  • Immunohistologic staining with monoclonal antibody
  • PCR
  • Slide agglutination
  • Single serology test
53
Q

fastidious, aerobic, motile, and non-carbohydrate fermenters legionnaires disease and pontiac ferer

A

Legionella

54
Q

Specimens for culture and direct examination for Legionella spp commonly include

A

sputum, bronchoalveolar lavage, and bronchial washings

55
Q

It is recommended to freeze Legionella spp. specimens at ___ if processing will be delayed for several days.

A

-70° C

56
Q

are pleomorphic, weakly staining, gram-negative bacilli that are approximatelv 1 to 2um × 0.5um in size

A

Legionella spp

57
Q

Extending the safranin counterstaining time to at least _ can enhance the staining intensity of the organisms

A

10 minutes

58
Q

agar that is best for Legionella isolation.

A

BCYE with 0.1% a-ketoglutaric acid (BCYEo)

59
Q

BCYEa agar, colonies appear as

A

rainbow/ grayish white or blue-green, convex, and glistening

60
Q

Characteristic “ground-glass” colony morphology

A

Legionella

61
Q

Legionella has a slow growth which takes

A

3-5 days

62
Q

Legionella Requires ___ for primary isolation

A

L-cysteine

63
Q

The ___ assay is the most common method employed for serologic diagnosis of legionellosis

A

indirect fluorescent antibody (IFA) assay

64
Q

small, gram-negative bacilli or coccobacilli, All are obligate aerobic bacteria, do not grow on ferment carbohydrates

A

Bordetella

65
Q

Bordetella grow best at _____

A

35 -37°C

66
Q

Bordetella are non motile except for

A

B. bronchiseptica

67
Q

constitute the specimen of choice for culture and PCR testing for Bordetella.

A

Nasopharyngeal aspirates or swabs of Dacron polyester with a nonwire shaft

68
Q

Transport media that can preserve viability of bordetella for up to 48 hours

A

casamino acid (1% casein hydrolysate) or amies with charcoal

69
Q

Isolation methods for bordetella

A

Bordet-Gengou potato infusion agar

70
Q

On Bordet-Gengou agar, colonies of B. pertussis and B. parapertussis

A

Hemolytic

71
Q

Transport system of B. Pertussis

A

• Casamino acid (1% casein hydrolysate)
• Amies transport medium with charcoal
• Regan-Lowe transport medium

72
Q

Most vibrio possess - flagella when grown in broth

A

Monotrichous or multitrichous flagella

73
Q

They have been described typically as curved or comma-shaped gram-negative rods, in gram stain

A

Vibrio

74
Q

The vibrios are facultatively anaerobic, are catalase and oxidase positive and able to reduce nitrate to nitrite, except for

A

V. metschnikovii,

75
Q

All species of vibrios, except for V. cholerae and V. mimicus are ___ or salt-loving

A

halophilic

76
Q

stool specimens suspected of containing Vibrio spp. should be collected and transported in

A

Cary-Blair medium

77
Q

is not acceptable, because glycerol is toxic to vibrios.

A

Buftered glycerol saline

78
Q

for specimens suspected of containing Vibrio spp. Feces is preferable, but rectal swabs are acceptable during the ___ of diarrheal illness.

A

acute phase of diarrheal illness.

79
Q

V. cholerae toxin can be detected in stool using an

A

enzyme-linked immunosorbent assay (ELISA) or a commercially available latex agglutination test

80
Q

When stool specimens from patients with cholera are examined using dark-field microscopy, the bacilli exhibit characteristic __\

A

rapid darting or shooting-star motility.

81
Q

on ___ or ___ vibrios produce medium to large colonies that appear smooth, opaque, and iridescent with a greenish hue.

A

SBA or (CHOC) agar,

82
Q

should also be examined for the presence of a- or -hemolysis for vibrio spp

A

SBA plate

83
Q

On this agar, the pathogenic vibrios usually grow as nonlactose fermenters (except for __)

A

MAC agar, (except for V. vulnificus )

84
Q

Vibrio isolate general susceptibility to the ___ (150mg) and ___,distinguishes them from Aeromonas.

A

vibriostatic agent 0/129 (150mg) and positive string test

85
Q

SUCROSE FERMENTERS
(YELLOW COLONIES)

A

V. CHOLERAE
V. ALGINOLYTICUS
V. METSCHNIKOVII

86
Q

NON-SUCROSE
FERMENTERS (GREEN
COLONIES)

A

V. MIMICUS
V. VULNIFICUS
V. PARAHEAMOLYTICUS
V. DAMSELA

87
Q

vibrio motility test: broth

A

polar sheated flagella

88
Q

vibrio motility test: Solid media

A

peritrichous, unsheathed flagella

89
Q

VIBRIO CHOLERAE is positive in what test

A

(+) oxidase, indole, lysine and ornithine
decarboxylase

90
Q

Stool cultures for Vibrio spp. are plated on the selective medium __ agar

A

thiosulfate citrate bile salts sucrose (TCBS) agar.

91
Q

2 biogroups of vibrio cholerae

A

Classical, el tor

92
Q

VP Test (Voges-Proskauer): for vibrio cholerae biogroup

A

• Classical: Negative (-)
• El Tor: Positive (+)

93
Q

Chicken RBC Agglutination: biotypes of Vibrio cholerae

A

• Classical: Negative (-)
• El Tor: Positive (+)

94
Q

Polymyxin B Sensitivity: biotypes of Vibrio cholerae

A

• Classical: Sensitive (S)
• El Tor: Resistant (R)

95
Q

It differentiates sucrose-fermenting ( yellow) from the nonsucrose-fermenting- (green)

A

Thiosulfate Citrate Bite Salts Sucrose Agar (TCBS)

Clinical Bacteriology Lab (4 decks)

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