Haemophilus

Abstract

Gr. neut. n. haima (Latin transliteration haema ), blood; N.L. masc. adj. philus (from Gr. masc. adj. philos ), friend, loving; N.L. masc. n. Haemophilus , blood‐lover. Proteobacteria / Gammaproteobacteria / Pasteurellales / Pasteurellaceae / Haemophilus Gram‐negative, nonmotile, facultatively anaerobic, pleomorphic rods, or coccobacilli with mesophilic growth. Propagation in vitro is facilitated by nutrients present in blood. Requirement for two blood components has been decisive for allocation to the genus, namely hemin (X factor) and nicotinamide adenine dinucleotide (NAD; V factor). Varying grades of capnophilia, and presence of 5–10% CO 2 may improve growth. Hemolysis is a characteristic of several species. Acid is produced from glucose, whereas arabinose, lactose, mannitol, sorbitol, and trehalose are not attacked. Nitrate is reduced, alkaline phosphatase is produced. Oxidase reaction is weak; catalase is variably present. The species of the genus are intimately associated with humans and certain animals, and typically restricted to a single host. Except Haemophilus ducreyi , the species are part of the commensal microbiota of mucosal surfaces and occasionally cause infections at other sites. The genus has been subjected to taxonomic rearrangements but is still polyphyletic, and additional classificatory alterations are justified. Member of the class Gammaproteobacteria , family Pasteurellaceae . DNA G + C content (mol%) : 37.3–46.0. Type species : Haemophilus influenzae Winslow et al. 1917 AL (basonyms: “Influenza‐bacillus” Pfeiffer 1892, “ Bacterium influenzae ” Lehmann and Neumann 1896).