GENOTYPIC AND PHENOTYPIC CHARACTERIZATION OF HELICOBACTER-CINAEDI ANDHELICOBACTER-FENNELLIAE STRAINS ISOLATED FROM HUMANS AND ANIMALS

By DNA-DNA hybridization, we classified 26 human strains, 4 dog and ca t strains, and ii hamster strains putatively identified as Helicobacte r cinaedi as well as 2 human strains and 2 animal strains of Helicobac ter fennelliae. All but one human strain belonged to the same hybridiz ation group as the type strain of H. cinaedi, The animal strains also appeared to belong to this hybridization group, Both human strains of H. fennelliae were shown to be H. fennelliae by DNA-DNA hybridization, but both animal strains were less than 15% related to the type strain , All strains were also characterized by plasmid profiles and ribotypi ng, Plasmids were found in 23% of the human strains, 100% of the hamst er strains, and 33% of the dog and cat strains, Human strains were ess entially identical by ribotyping, but were clearly differentiated from the hamster and dog and cat strains, Some strains may be difficult to culture on primary isolation; we found that our strains grew well on anaerobic CDC agar, brucella agar, and tryptic soy agar II, Our H. cin aedi and H. fennelliae strains differed from those previously describe d because some were resistant to cephalothin; some H. cinaedi strains were also resistant to nalidixic acid, All isolates were also characte rized by antimicrobial susceptibility testing, We found that human str ains of H. cinaedi were more resistant to clindamycin and erythromycin than were animal isolates; 19% of the human strains were resistant to ciprofloxacin, Therefore, we recommend that antimicrobial susceptibil ity results be obtained before initiating therapy for H. cinaedi and H . fennelliae infections.