Corynebacterium guaraldiaesp. nov.: a new species of Corynebacteriumfrom human infections

Non-diphtheria Corynebacteriumspecies (NDC) belonging to the human skin and mucosa microbiota are frequently neglected as contaminants. However, reports of human infections by Corynebacteriumspp. have increased considerably in recent years. In this study, a group of six NDC isolates of urine (n= 5) and sebaceous cyst (n= 1) from two South American countries were identified at genus level or misidentified based on API® Coryne and genetic/molecular analyses. The 16S rRNA (99.09–99.56%) and rpoB (96.18–97.14%) gene sequence similarities of the isolates were higher when compared with Corynebacterium aurimucosumDSM 44532T. Multilocus sequence analysis (MLSA) indicated that these six NDC isolates compose a distinctive phylogenetic clade. Genome-based taxonomic analysis with the whole-genome sequences was able to separate these six isolates from other known Corynebacteriumtype strains. Average nucleotide identity (ANI), average amino acid identity (AAI), and digital DNA–DNA hybridization (dDDH) values between closely related type strains and the six isolates were considerably lower than the currently recommended threshold values for species circumscription. Phylogenetic and genomic taxonomy analyses indicated these microorganisms as a novel Corynebacteriumspecies, for which we formally propose the name Corynebacterium guaraldiaesp. nov. with isolate 13T(= CBAS 827T= CCBH 35012T) as type strain.