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[9d] MODULE 6 UNIT 4: Fastidious, Gram-negative Bacilli > LABORATORY > Flashcards

LABORATORY Flashcards

1
Q

Haemophilus influenzae: Specimens

A
  • Cerebrospinal fluid
  • Sputum, other types of respiratory specimens
  • Blood
  • Pus
  • Material from genital ulcer (H. ducreyi)
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2
Q

small, palestaining, gram-negative coccobacilli. Occasionally, slender filamentous cells may be observed

A

Haemophilus species

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3
Q

pale-staining, gram-negative coccobacilli, often arranged in clustered groups (“school of fish”) or loosely coiled parallel chains (“railroad tracks”)

A

H. ducreyi

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4
Q

morphology is rarely seen in clinical specimens

A

H. ducreyi

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5
Q

Organisms may be inside and outside of polymorphonuclear leukocytes (PMNs).

A

H. ducreyi

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6
Q

Used for rapid diagnosis of H. influenzae type b infections.

A

Antigen detection

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7
Q

[?] or other commercially available methods for the detection of the type b capsular antigen in CSF,, serum, and urine.

A

Neufeld-Quellung reaction

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8
Q

prepared by adding rabbit or horse blood to an agar base when the temperature of the medium is high enough (about 80°C) to lyse the red cells to release the growth factors without inactivating V factor (NAD), which is heat-labile

A

Chocolate Agar

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9
Q

is not suitable for recovery of Haemophilus species that require V factor for growth

A

Conventional sheep blood agar

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10
Q

Conventional sheep blood agar contains X factor but not V factor because of the presence of [?] in native sheep blood.

A

V-factor-inactivating enzymes

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11
Q

It is a selective medium containing beef heart infusion, peptones, yeast extract, and defibrinated horse blood (5%) containing both X and V factors.

A

Haemophilus Isolation Agar

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12
Q

is added to inhibit the other normal respiratory tract flora.

A

Bacitracin (300 µg/mL)

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13
Q

Other isolation media that provide both X and V factors:

A

i. Casman’s Agar with 5% lyzed blood
ii. Fildes enrichment agar
iii. Levinthal agar

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14
Q

Principle:
Several bacterial species, including Staphylococcus aureus, produce V factor (NAD) as a metabolic by-product. Therefore tiny colonies of Haemophilus species. may be seen growing on sheep blood agar very close to colonies of bacteria capable of producing V factor; this is known as the satellite phenomenon (or satellitism).

A

Staphylococcus Streak Technique (using 5% Sheep BAM)

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15
Q

Procedure:

i. A colony of a suspected Haemophilus species is subcultured onto a sheep blood agar plate and streaked as a lawn.
ii. A single streak of hemolytic strain of S. aureus is made through the lawn inoculum.
iii. Incubate overnight in a CO2- enriched environment at 35°C to 37°C.
iv. Staphylococcus synthesizes V factor, and lyses the red blood cells adjacent to the streak line, releasing X factor and V factor providing the necessary components for growth of Haemophilus species.

A

Staphylococcus Streak Technique (using 5% Sheep BAM)

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16
Q

Result:
Tiny moist gray colonies of the haemophili may be observed within the hemolytic area adjacent to the staphylococcal growth. Haemophilus colonies are larger at the vicinity of the staphylococcal colonies.

A

Staphylococcus Streak Technique (using 5% Sheep BAM)

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17
Q

small, gray glistening colony is H. influenzae.

A

Haemophilus influenzae satellitism

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18
Q

Incubation

  • 35-37°C
  • 5% to 10% CO2 atmosphere (using candle extinction jar, or CO2 incubator)
  • Colonies can be observed within 24 hours, but cultures are routinely held 72 hours before being discarded as negative.
A

Haemophilus influenzae

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19
Q 
Principle: 
X factor (hemin, hematin) and V factor (NAD) are required either singly or in combination to support the growth of various species of Haemophilus on agar media. X and V factors, each being water soluble, readily diffuse in agar culture media.
A

Test for Factor Requirement

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20
Q

Procedure:
i. Filter paper disks or strips impregnated with these factors, which are commercially available, are placed on the surface of a medium deficient in these factors, such as trypticase-soy agar or brain–heart infusion agar, which has been inoculated as a lawn with the test organism.
ii. Incubate the plate in CO2 atmosphere at 35°C for 18–24 hours.
iii. Factor requirements of the organism are
then determined, a f t e r o v e r n i g h t i n c u b a t i o n , b y o b s e r v i n g t h e patterns of growth around the paper strips or disks.

A

Test for Factor Requirement

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21
Q

A better test for X factor requirement.

A

Porphyrin Test

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22
Q

[?] detects the presence of enzymes that convert δaminolevulinic acid (ALA) into porphobilinogen, porphyrins, protoporphyrins, and heme.
Haemophilus species that possess the enzyme can synthesize [?], therefore, do not require exogenous X factor for growth.

A

Porphyrin Test

protoporphyrin

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23
Q

Procedure:
The test may be performed in broth, in agar, or on a disk.
i. With the ALA broth or agar medium, the organism is inoculated onto the medium and incubated overnight.
ii. With the disk method, the impregnated disk is moistened with water and inoculated with colonial growth, and incubated for 4 hours. After incubation, growth is examined under an ultraviolet light (Wood’s light).

A

Porphyrin Test

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24
Q

Results:
(+) Brick-red fluorescence - indicates the presence of porphyrins, does NOT require X factor.
(-) Bluish fluorescence

A

Porphyrin Test

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25
Q

Nasophayngeal swab or aspirate is the preferred specimen

A

Bordetella pertussis

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26
Q

Very small, gram-negative coccobacilli.

A

Bordetella pertussis

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27
Q

Fluorescent antibody (FA) reagent (stain using polyclonal antibodies against B. pertussis or B. parapertussis) can be used to examine nasopharyngeal swab specimens.

A

Direct fluorescent antibody (DFA)

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28
Q

potato-blood-glycerol agar

A

Bordet-Gengou Agar

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29
Q

Potato infusion provides

A

nitrogen and vitamins

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30
Q

[?], present from the potato infusion, absorbs fatty acids which inhibits growth of B. pertussis.

A

Starch

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31
Q

is a carbon source.

A

Glycerol

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32
Q

provides essential complex growth factors.

A

15% sheep or horse blood

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33
Q

charcoal, cephalexin blood agar (CCBA)

A

Regan-Lowe Agar

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34
Q

supplies nutrients required for the cultivation of Bordetella species.

A

Defibrinated horse blood

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35
Q

promotes growth of B. pertussis.

A

Nicotinic acid (niacin, vitamin B3)

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36
Q

neutralize substances toxic to Bordetella species, such as fatty acids and peroxides.

A

Charcoal and starch

37
Q

is a cephalosporin antibiotic that inhibits most normal flora of the nasopharynx.

A

Cephalexin

38
Q
  • 35-37°C
  • Aerobic, humidified atmosphere
  • generally requires 2-6 days to grow; but, must be held for up to 12 days before reporting as negative.
A

B. pertussis

39
Q

produces small, domed, glistening colonies that resemble “mercury droplets” , “bisected pearls”, or “aluminum paint”

A

B. pertussis

40
Q

[?] is not distinct for the identification of other Bordetella species

A

colony morphology

41
Q

Blood or bone marrow are the specimens of choice

A

Brucella species

42
Q

• Other specimen:

  • Cerebrospinal fluid (CSF)
  • Pleural fluid
  • Synovial fluids
  • Urine
  • Abscesses
  • Other tissues
A

Brucella species

43
Q

Faintly staining, minute gram-negative coccobacilli

A

Brucella species

44
Q

Blood and bone marrow specimens are inoculated into aerobic and anaerobic bottles, and because of their slow growth rates, conventional blood cultures should be incubated at 35°C for 3 weeks with blind subcultures into plated media.

A

Brucella species

45
Q

Culture media for Brucella species

A
  1. Blood Agar (or Chocolate Agar) with 5% horse blood

2. Brucella Agar with 5% horse blood

46
Q
  • 35-37°C
  • 5% to 10% CO2 in a humidified atmosphere.
  • Most isolates can be detected within 5 to 7 days. Cultures should be retained for 3 weeks before they are considered negative and discarded.
A

Brucella species

47
Q

Colonies appear small, convex, smooth, translucent, gamma-hemolytic, and slightly yellow and opalescent after at least 48 hours of incubation.

A

Brucella species

48
Q

It uses a biphasic medium consisting of tryptose agar and tryptose broth in one bottle.

A

Castañeda’s Method of Blood Culture

49
Q

The inoculum is added to the broth medium and when subcultures are to be made, the bottle is simply tilted to allow the broth to flow over the agar slant.

A

Castañeda’s Method of Blood Culture

50
Q

There is NO need for frequent opening of the culture bottle to subculture; thus, reduces chances of contamination and increases the chances of isolation.

A

Castañeda’s Method of Blood Culture

51
Q

small, Gram-negative coccobacilli, which is strictly aerobic, nonmotile, non-spore-forming and weakly catalase positive.

A

Francisella tularensis

52
Q

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

A

Francisella tularensis

53
Q

Many species of animals, esp. rabbits, deer, and

rodents are the reservoir

A

Francisella tularensis

54
Q

Humans are infected by the bite of an arthropod vector (deerfly, ticks, mites, or lice) deerfly or tick;
by traumatic implantation on contact with infected
animal tissues; by ingestion of undercooked,
infected meat. or contaminated water; and also,
inhalation of the organism.

A

Francisella tularensis

55
Q

It is a highly infectious agent that as few as 10 - 50 organisms can cause an infection

A

Francisella tularensis

56
Q

facultative intracellular pathogen that localizes in reticuloendothelial cells.

A

Francisella tularensis

57
Q

a disease of many names, including rabbit fever, deerfly fever, lemming fever, and water rat trapper’s disease

A

tularemia

58
Q

A sudden onset of flu like symptoms (malaise, headache, fever, chills) and painful swollen lymph nodes are observed in infected individuals.

A

tularemia

59
Q

s the most common type, which typically presents with a skin ulcer, usually as the result of a tick bite.

A

Ulceroglandular tularemia

60
Q

The [?] at the site of infection is followed by septicemia with rapid spread to the liver and spleen; 30 percent of untreated patients die.

A

local abscess

61
Q

[?] types are the other major syndromes that are

associated with tularemia which is influenced by the mode of infection.

A

Pulmonary (pneumonia) and gastrointestinal (typhoid-like)

62
Q

Lab identification can be made using a medium called [?]. Most hospital laboratories don’t process this organism, however, because it is
highly contagious.

A

cysteine-blood agar

63
Q

Protection from [?] is afforded by live attenuated vaccines and protective gloves, masks and eyewear for laboratory workers and other occupationally exposed personnel.

A

F. tularensis infection

64
Q

Gram-negative coccobacilli with a bipolar appearance or may appear ovoid, filamentous, or as bacilli on stained smears

A

Pasteurella species

65
Q

They are aerobes or facultative anaerobes that grow readily on ordinary bacteriologic media.

A

Pasteurella species

66
Q

nonmotile, catalase positive, oxidase positive, and ferment glucose with weak to moderate acid production without gas

A

Pasteurella species

67
Q

is the species which most commonly infects humans causing pasteurellosis

A

P. multocida

68
Q

Humans can acquire the organism from dog or cat bites.

A

P. multocida

69
Q

can quickly progress resulting in inflammation and exudate production.

A

Wound infections

70
Q

On occasion, [?] (septicemia, arthritis, endocarditis, osteomyelitis, meningitis) and [?] forms are also possible.

A

systemic

pneumonic

71
Q

It grows well on medium with [?] and [?], developing in 48 hours at 35-37 oC, small (1-2 mm), smooth, moist to mucoid colonies with a greenish or brownish discoloration, and musty odor resembling smell of mushroom.

A

blood and hemin

72
Q

thin, pleomorphic, weakly-staining, gram-negative

bacilli; weakly oxidase and catalase positive, and often are motile

A

Legionella pneumophila

73
Q

can only be grown on complex media due to their fastidious nutritional requirements

A

Legionella pneumophila

74
Q

The primary growth factor required is , a nutrient that is also essential for F. tularensis.

A

L-cysteine

75
Q

is also essential, and other compounds are necessary for optimal growth.

A

Ferric iron

76
Q

Energy is derived from [?] rather than carbohydrates.

A

amino acids

77
Q

is ubiquitous and has the ability to survive and persist in natural habitats and humanmade water supplies and distribution systems. It is widely distributed in aqueous habitats such as tap water, cooling towers, spas, ponds, and other fresh waters.

A

Legionella pneumophila

78
Q

Transmission to humans occurs through inhalation
of aerosols from contaminated water, esp. from air
conditioning system. Human-to-human infection
and laboratory-acquired infections are not known
to occur.

A

Legionella pneumophila

79
Q

facultative intracellular pathogen in alveolar macrophages

A

Legionella pneumophila

80
Q

The most common presentation is acute pneumonia, which varies in severity from mild illness that does not require hospitalization (“walking pneumonia”) to fatal multilobar pneumonia. Typically, patients have high fever and cough but do not produce much sputum, a clinical picture that does not resemble typical pneumonia, thus is also referred to as “atypical pneumonia”.

A

Legionnaire’s disease

81
Q

Extrapulmonary infections occur with or without pneumonia and has been associated with bacteremia, renal failure, liver function abnormalities, watery diarrhea, nausea, vomiting, headache, confusion, lethargy, and other CNS abnormalities.

A

Legionnaire’s disease

82
Q

A milder, non-pneumonic form of legionellosis, resembling influenza.

A

Pontiac fever

83
Q

Patients are previously healthy individuals who complain of flulike symptoms of fever, headache, and myalgia that last 2 to 5 days and then subside without medical intervention.

A

Pontiac fever

84
Q

The medium of choice is [?], containing yeast extract, iron, Lcysteine, and a-ketoglutarate for bacterial growth; activated charcoal to inactivate toxic peroxides that develop in the media; and buffer with pH 6.9, the
optimum for growth of the organisms.

A

buffered charcoal-yeast extract (BCYE)

85
Q

For contaminated specimens such as sputum, [?] should be added. Bacterial colonies that are round or flat with entire edges can usually be detected within 3 to 5 days and identified presumptively as [?].

A

antibiotics

Legionella

86
Q

pleomorphic gram-negative bacilli frequently occurring in chains or long filaments, and often with a series of oval to elongated bulbous swellings, giving a string-of-beads appearance. It is nonencapsulated, facultative anaerobic, nonmotile, and fermentative.

A

Streptobacillus moniliformis

87
Q

It occurs as indigenous flora in the upper respiratory
tract of rodents and is usually transmitted to humans by bites or scratches from rodents or carnivores that ingest rodents; or less commonly, after ingestion of food contaminated by rodent excrement or by traumatic injury.

A

Streptobacillus moniliformis

88
Q

It causes streptobacillosis (“rat bite fever” or Haverhill fever). Local lymphangitis and lymphadenitis may develop up to 3 weeks later, followed by fever, chills, malaise, and, later, a general morbilliform maculopapular or petechial rash. A migratory polyarthritis develop in some patients.

A

Streptobacillus moniliformis

89
Q

Bacteria grow slowly up to 6 days in thioglycollate broth as colonies with a puffball, cotton ball), or bread crumbs appearance.

A

Streptobacillus moniliformis

[9d] MODULE 6 UNIT 4: Fastidious, Gram-negative Bacilli (2 decks)

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