Campylobacter hominis sp nov., from the human gastrointestinal tract

Sequences of 16S rDNA of a novel campylobacter from faeces of healthy human s were previously shown to originate from a new taxon, 'Candidatus Campylob acter hominis', which could not be cultured. Since phylogenetic analysis su ggested that anaerobic conditions might be required for growth, an isolatio n strategy was developed employing initial non-selective membrane filtratio n onto fastidious anaerobe agar. Campylobacters were then isolated from the resulting mixed microbial flora by a dilution strategy and/or by immunomag netic separation with genus-specific polyclonal antibody. Isolates were ide ntified by a genus and taxon-specific PCR assay, and 16S rDNA nucleotide se quence analysis was carried out. All isolates exhibited the typical Campylo bacter characteristics of being non-fermentative, oxidase-positive, catalas e-negative and Gram-negative. Unusually, however, they were straight rods l acking flagella. The 16S rDNA nucleotide sequence analysis, DNA and mol% GC were consistent with a new Campylobacter species whose nearest phylogenet ic neighbours were Campylobacter gracilis and Campylobacter sputorum. The u nique species status of the isolates was further confirmed by taxonomic ana lysis of 47 phenotypic characteristics. The name Campylobacter hominis sp. nov. is proposed for the new species, the type strain of which is NCTC 1314 6(T)(= LMG 19568(T)).