First isolation of Campylobacter vicugnae sp. nov. in humans suffering from gastroenteritis

Abstract

The present study describes the first isolation of a recently described Campylobacter species, Campylobacter vicugnae , in humans. The isolates were recovered by two independent French laboratories in 2020 and 2022 from a man and a woman suffering from gastroenteritis. Biochemical and growth characteristics, and electron microscopy for these two strains indicated that they belong to Campylobacter genus. 16S rDNA and GyrA-based phylogeny, as well as average nucleotide identity and in silico DNA-DNA Hybridization analyses revealed that both strains belong to the Campylobacter vicugnae species. Both isolates possess a complete cytolethal distending toxin (CDT) locus with cdtA , cdtB, and cdt C, and features of CDT activity were demonstrated in vitro with Caco-2 intestinal epithelial cells. Our data suggest that these two isolates of C. vicugnae were associated with gastroenteritis in humans and induced major cytopathogenic effects in vitro . C. vicugnae is likely to be a novel human pathogen, with a source of foodborne infection that needs to be determined. IMPORTANCE Campylobacter species that display toxicity features are a worldwide public health issue. In clinical contexts, it is crucial to identify which isolate could be an urgent threat to a patient. Actual and widely used laboratory methods such as mass spectrometry or PCR may be flawed in the field of species identification. In contrast, the present study shows that next-generation sequencing allows to precisely identify isolates to species level that may have been omitted otherwise. Moreover, it helps to identify emerging species before they become a threat to human health. Recovery of a new Campylobacter species in human sample, such as the new species “ Campylobacter vicugnae ,” is an important step for the identification of emerging pathogens posing threat to global health.