Haemophilus influenzae: Comparison of respiratory tract isolates with genitourinary tract isolates

Abstract

Haemophilus influenzae isolates recovered from the genitourinary (GU) tract were shown to have a significantly different biotype distribution compared with respiratory tract isolates. Biotype IV strains were recovered more commonly from the Gu tract, and most strains were non-serotypable. Antibiotic-susceptible strains isolated from the GU tract more frequently harbored plasmids of <10 megadaltons than did antibiotic-susceptible respiratory tract strains. One 2.8-resident in a respiratory tract isolate were shown to be related to the small ampicillin resistance plasmids previously described in H. influenzae, Haemophillus parainfluenzae. Haemophilus ducreyi, and neisseria gonorrhoeae. This supports the suggestion that these ampicillin resistance plasmids originated by transposition or recombination of the ampicillin transposon (TnA) with cryptic endogenous Haemophilus plasmids.