Streptococcus vulneris sp. nov., isolated from wound of patient with diabetic foot ulcer (DFU)

Abstract

A new α-haemolytic streptococcal strain, designated DM3B3^T, was isolated from the wound of a diabetic foot ulcer (DFU) patient. Phylogenetic analysis based on 16S rRNA full-gene sequencing (1563 bp) revealed highest sequence similarity to Streptococcus mitis (99.7%), followed by "Streptococcus gwangjuense" (99.6%), and Streptococcus pseudopneumoniae (99.5%). Comparison of five housekeeping genes, groEL, rpoB, sodA, recA and pheS, revealed that strain DM3B3^T was well separated from the Streptococcus reference strains. The complete genome of strain DM3B3^T consisted of 1,963,039 bp with a G + C content of 41.0 mol%. Average nucleotide identity values between strain DM3B3^T and Streptococcus mitis NCTC 12261^T, "Streptococcus gwangjuense" ChDC B345^T, and Streptococcus pseudopneumoniae ATCC BAA-960^T were 93.8%, 94.4%, and 92.2%, respectively. The highest digital DNA-DNA hybridization value with respect to the closest species was 57.5%, i.e., below the species cut-off of 70% hybridization. The main cellular fatty acids of strain DM3B3^T were 16:0, 18:1ω7c, 18:1ω9c and 18:0. On the basis of phylogenetic, genotypic and phenotypic data, we propose to classify this isolate as representative of a novel species of the genus Streptococcus, Streptococcus vulneris sp. nov., in reference to its isolation from wound, with strain DM3B3^T (= NBRC 114638^T = BCRC 81288^T) as the type strain.

Keywords: Diabetic foot ulcer; Streptococcus vulneris; Wound.