Isolation and characterization of a newly identified Haemophilus species from cats: "Haemophilus felis".

A gram-negative coccobacillus was isolated from the lower respiratory tract of a cat with chronic obstructive pulmonary disease. The isolate required CO2 and V factor for growth and was initially identified as Haemophilus paraphrophilus on the basis of its nutritional requirements, colony morphology, and some biochemical tests. Because of the host specificity of Haemophilus species and discrepancies in catalase, oxidase, and hemolytic activities, additional testing was done. Extensive biochemical testing, G+C content, and DNA reassociation studies indicated that the organism was distinct from other Haemophilus species. Therefore, the organism was identified as a previously unrecognized Haemophilus species and was tentatively named "Haemophilus felis." Bacteria identical to the original isolate were isolated from the nasopharynxes of 6 of 28 apparently normal cats, indicating that H. felis or H. felis-like organisms may be common members of the feline upper respiratory tract flora.