Module 2: Haemophilus Flashcards
The original criterion for placing an organism in the Haemophilus genus
Requirement for a growth factor derived from blood
Cellular morphology of Haemophilus influenzae
Pleomorphic Gram negative coccobacilli
The intensity of stain for Haemophilus in Gram stain preparations may be improved by:
Counterstaining with carbol fuchsin instead of safranin
The Haemophilus species most commonly seen as a human pathogen is:
Haemophilus influenzae
CO2 requirements of Haemophilus influenzae
Most strains enhanced by increased CO2
Best medium for isolation of Haemophilus influenzae
Chocolate agar
Why does sheep blood agar not support the growth of Haemophilus influenzae?
Enzymes in sheep blood inactivate V factor
The best bacterial source of V factor for growth of Haemophilus
Staphylococcus aureus
Colonial morphology of H influenzae on chocolate agar
Small, raised, gray and translucent with a “sweet mousy” odor
1-4mm
May be mucoid
A non hemolytic Haemophilus that requires both X and V factors for growth
Haemophilus influenzae
The porphyrin test determines the ability of an organism to:
Synthesize X factor from delta aminolevulinic acid
The most virulent strain of H influenzae
Type b
How can H influenzae be detected directly from spinal fluid?
Co-agglutination reagent
Susceptibility of H influenzae to ampicillin
Up to 30% are reported to be resistant
Resistance of H influenzae to ampicillin is usually caused by:
Beta lactamase production
