Haemophilus

Abstract Haemophilus spp. are members of the family Pasteurellaceae . Members of the Haemophilus genus are small, nonmotile, non‐spore‐forming, non‐acid‐fast, pleomorphic, Gram‐negative bacilli with fastidious growth requirements. Haemophilus spp. can be found as part of the commensal microbiota of mucous membranes in humans. H. influenzae may also be found as part of the commensal bacterial microbiota of the mucosal surfaces of the upper respiratory tract (URT) of many healthy individuals; however, asymptomatic colonization of the URT with encapsulated strains of H. influenzae type b is rare. Isolates of H. influenzae constitute a diverse group of organisms that cause a broad range of human diseases. Collection of specimens for the diagnosis of Haemophilus infections is predicated on the nature of the infection being evaluated.