Corynebacterium drakensteinense sp. nov., isolated from the nasopharynx of a healthy South African infant.

Emerging evidence supports the role of the nasopharyngeal microbiome in respiratory health, including association with conditions such as asthma and respiratory tract infections. One dominant commensal genus is Corynebacterium, members of which are commonly present in the nasopharynx of infants. These commensal Corynebacterium spp. have been reported to correlate with respiratory health. In this paper, we present isolate MNWGS58T isolated from the nasopharynx of a South African infant. Genomic analysis of the whole-genome sequence of MNWGS58T revealed that it is phylogenetically closely related to other Corynebacterium spp. found in the nasopharynx, Corynebacterium propinquum [85% average nucleotide identity (ANI)] and Corynebacterium pseudodiphtheriticum (84% ANI). Bacterial identification using matrix-assisted laser desorption/ionization time-of-flight MS identified MNWGS58T as C. pseudodiphtheriticum. The API Coryne assay identified the novel isolate as C. propinquum, and the VITEK 2 ANC assay identified the novel isolate as Corynebacterium otitidis. Both genomic analyses and phenotypic analyses show striking similarities to C. propinquum and C. pseudodiphtheriticum. The cell wall is consistent with closely related Corynebacterium spp., albeit with a higher C17:0 content. The genome is 2.48Mbp with a G+C content of 56.9 mol%. Digital DNA-DNA hybridization values for MNWGS58T were low when compared to C. pseudodiphtheriticum MNWGS56 and C. propinquum MNWGS51 (27.4 and 28.4%, respectively). Although there are phenotypic similarities, 85% ANI with the closest Corynebacterium spp. strongly supports the classification of a novel species of Corynebacterium, for which we propose the name Corynebacterium drakensteinense sp. nov., with the type strain MNWGS58T (=TSD-445T=NCTC 15058T). It will be important to elucidate the role of this novel species of Corynebacterium in the human nasopharynx and identify additional niches for this species in future studies.