Clostridium perfringenosumsp. nov., a closely related species toClostridium perfringensand its virulence factors, isolated from a human soft tissue infection

Abstract

AbstractTwo Gram-positive, anaerobic bacteria, designated 27733 and 27737, were isolated from a soft tissue infection from a human patient. They were preliminarily identified asClostridium perfringensthrough a series of phenotypic tests, including Gram-staining, determination of lipase and hemolytic activities, MALDI-ToF profiling, and a commercial biochemical identification system. In line with these results, genomes obtained for both isolates were ~3.56 Mbp in size, showed a DNA G+C content of ~28.4%, and containedC. perfringensribosomal markers (i.e. 16S rRNA gene identity >99.0% toC. perfringensATCC13124T). A closer examination of these sequences; however, revealed low average Nucleotide Identity (~87%) and digital DNA-DNA Hybridization (~35%) values between isolates 27733/27737 andC. perfringensATCC13124T, as well as substantial differences in gene content to multipleC. perfringensstrains, indicating that they represent a novel species within the genusClostridium.Congruently, Bayesian dating analyses placed the divergence of this new species andC. perfringensfrom its common ancestor hundreds of thousands of years ago. Isolates 27733/27737 are not genomically identical (34-197 SNPs apart) and carry genes forC. perfringens-liketoxins (<94% nucleotide sequence identity), includingplc(alpha toxin),pfoA(perfringolysin O, theta-toxin),nagHIJKL(hyalorudinase, mu-toxin),nanHIJ(exo-alpha sialidase), andcloSI(alpha-clostripain). They do not have known antibiotic resistance genes but were catalogued as resistant to clindamycin through phenotypic tests. On the basis of the presented evidence, and due to its resemblance and potential confusion withC. perfringens,we herein propose the speciesC. perfringenosumsp. nov. and strain 27733 as its type strain.