Haemophilus

Haemophilus spp sharing the family traits of pasteurellaceae,Gram-negative bacilli or coccobacilli, non-motile, non-spore forming, capsule can be produce by H.influenzae and H.paragallinarum,oxidase-positive, fermented carbohydrates.

Haemophilus spp had to have one or both of growth factors: -V factor which is coenzyme found in the blood (nicotinamide adenine dinucleotide :NAD),this factor can also produce by Staphylococcus ,and its heat labile. -X factor:which is hematin or haemin, its heat stable.

They are nutritionally fastidious, will not grow on MacConkey agar and grow best on chocolate agar which is a medium naturally containing the growth factors (V&X) it’s a blood agar prepared by addition of a blood when melted agar is at 75 c to 80 c (rather than 50 c when making regular blood agar) this procedure liberate NAD from cells and inactivates enzymes destructive to NAD.

Haemophilus influenzae cultivated on chocolate agar

A feeder bacterium (e,g, Staphylococcus aureus) may be inoculated a cross plates where Haemophilus has been streaking , growth occurs only near the feeder streak this phenomenon called satellitism.

``Satellitism and satellitism test procedure to identify Haemophilus influenzae ````````````````````````````````````

Haemophilus species are: H. influenzae, H. suis, H. parasuis, H Haemophilus species are: H.influenzae, H.suis, H.parasuis, H.gallinarum, H.paragallinarum, H.somnus  

Diseases of Haemophilus spp Host Diseases Meningitis, septicemia, otitis, conjunctivitis, bronchopneumonia Human H.influenzae Pneumonia, Glassers disease Swine H.Suis Secondary Pneumonia, , Glassers disease H.parasuis Fowl coryza Fowl H.gallinarum Infectious coryza H.paragallinarum Septicemia, meningioencephalitis, pneumonia, abortion,apididymitis Cattle & sheep H.somnus

Infectious Coryza

Laboratory diagnosis Haemophilus species should be protected from drying and cultured as soon as possible within 24hrs after collection. Direct microscopy Observation of smallGram-negative rods

Isolation X and V factors must be supplied Isolation X and V factors must be supplied. Chocolate agar is the most satisfactory medium for haemophili isolated from animals Fowl coryza can be diagnosed by agglutination, agar gel immunodiffusion and hemagglutination-inhibition test.   Colonial morphology Small dewdrop-like colonies may appear after 24-48 hrs.’ incubation,non haemolytic on blood agar.

Resistance Haemophilus spp are readily killed by heat and disinfectants, and die rapidly in culture. H.paragallinarumcan survive in exudates for several days. Pathogensis The antiphagocytosis capsules and heat-labile cytotoxic factors of Haemophilusspp strains are suspected virulence factors. The lesions ofHaemophilus infections also suggested endotoxins involvement. Other factors like adheres to epithelium and endothelium, resistant to phagocytic killing. All infections have suppurative component. Infection of lungs, body cavities and joints are serofibrinousto fibrinopurulent.

Bacterial colonization of the meningeal vessels produces athrombotic vasculitis leading to encephalitis and meningitis,haemorrhagic necrotising processes. Fowl coryza is marked by catarrhal inflammation with heterophil exudates.   Treatment and control Most animal haemophilli are susceptible to penicillin G,ceftiofur and tetracycline For fowl coryza therapy erythromycin or sulfonamide can be administered in feed or water. Infectious coryza of fowl is controlled by elimination of carriers and immunization of individuals at risk.