Module 2: Haemophilus Flashcards

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1
Q

The original criterion for placing an organism in the Haemophilus genus

A

Requirement for a growth factor derived from blood

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2
Q

Cellular morphology of Haemophilus influenzae

A

Pleomorphic Gram negative coccobacilli

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3
Q

The intensity of stain for Haemophilus in Gram stain preparations may be improved by:

A

Counterstaining with carbol fuchsin instead of safranin

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4
Q

The Haemophilus species most commonly seen as a human pathogen is:

A

Haemophilus influenzae

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5
Q

CO2 requirements of Haemophilus influenzae

A

Most strains enhanced by increased CO2

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6
Q

Best medium for isolation of Haemophilus influenzae

A

Chocolate agar

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7
Q

Why does sheep blood agar not support the growth of Haemophilus influenzae?

A

Enzymes in sheep blood inactivate V factor

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8
Q

The best bacterial source of V factor for growth of Haemophilus

A

Staphylococcus aureus

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9
Q

Colonial morphology of H influenzae on chocolate agar

A

Small, raised, gray and translucent with a “sweet mousy” odor
1-4mm
May be mucoid

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10
Q

A non hemolytic Haemophilus that requires both X and V factors for growth

A

Haemophilus influenzae

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11
Q

The porphyrin test determines the ability of an organism to:

A

Synthesize X factor from delta aminolevulinic acid

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12
Q

The most virulent strain of H influenzae

A

Type b

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13
Q

How can H influenzae be detected directly from spinal fluid?

A

Co-agglutination reagent

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14
Q

Susceptibility of H influenzae to ampicillin

A

Up to 30% are reported to be resistant

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15
Q

Resistance of H influenzae to ampicillin is usually caused by:

A

Beta lactamase production

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16
Q

The presence of acetyl transferase indicates resistance to:

A

Chloramphenicol

17
Q

The species of Haemophilus responsible for an STI

A

Haemophilus ducreyi

18
Q

Typical direct smears of H ducreyi cellular morphology

A

Gram negative coccobacilli arranged in typical clusters or “schools of fish”

19
Q

What affects the suitability of chocolate agar for growing Haemophilus

A

The time for chocolatizing and the temperature used for chocolatizing

20
Q

3 genera in the family Pasteurellaceae

A

Haemophilus
Actinobacillus
Pasteurella