Haemophilus influnzae

Haemophilus influnzaeThis genus is frequently found in the healthy human threat and is also associated with infection of the respiratory tract it cause secondary infection after viral influenza disease

Morphology and staining

Gram Negative ,polymorphic bacteria, it mean some time appear cocci, or like bacilli , non motile , capsulate in young cultures non spore forming facultative anaerobic bacteriaMorphology and staining

Cultural characters

Pathogenicity

Non capsulated strains of H.influenzae are commensalism of the respiratory tract of man , they may attack the mucous membrane it case secondary infection after viral influenza disease. capsulated strains cause meningitis in children .

Lab. Diagnosis

Specimens :-1-sputum from respiratory infections 2-C.S.F. from cases of meningitis 1-Direct Gram staining of the sputum is not useful because it is difficult to identify. Gram stain of C.S.F show capsulated gram negative bacilli.2- The specimens are inoculated on the following media 1-chocolate agar2-fildes agar (enriched media for haemophilus)3-Blood agar in which staphylococcus is also inoculated (to dominstrate sattilitism)

3-Identification of Haemophilus spp. by their growth requirements for hemin (X factor) and NAD (V factor) and -hemolysis on horse blood agar