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Updated: Jan 9, 2026

Heuristic Mining of Hierarchical Genotypes and Accessory Genome Loci in Bacterial Populations
Published on: December 7, 2021
Prevalence and genetic characteristics of Staphylococcus capitis proto-NRCS-A clone among colonizing isolates from
Mina Hirose1, Meiji Soe Aung2, Yukito Hirose3
1Division of Pediatric Dentistry, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Ishikari, Tobetsu 061-0293, Japan.
Objectives:
S. capitis is among the coagulase-negative staphylococci (CoNS) and a commensal bacterium in humans. However, a virulent clone designated NRCS-A has been reported to be responsible for outbreaks of neonatal sepsis, primarily in Europe. This clone harbors virulence factors nsr and tarJ, and carries a type V SCCmec, showing multiple antimicrobial resistance. This study explored the prevalence of the (proto-)NRCS-A clone in healthy individuals and their genetic characteristics in Japan.
Methods:
Staphylococci colonizing on the hand skin and the oral cavity of healthy individuals were isolated and analyzed for the species/subspecies by sequencing of 16S rRNA and arcC. The presence of virulence factors and antimicrobial resistance-associated genes were detected by PCR and sequencing. S. capitis isolates were genetically classified by double-locus (arcC-rpoB) sequence typing and peptide profile of PSMβ.
Results:
Among 221 isolates of CoNS (19 species) recovered from 444 healthy adults, 82 isolates were identified as S. capitis. Virulence factors associated with the NRCS-A clone, i.e., nsr, tarJ, and ebh were detected in 29 %, 11 %, and 51 % of isolates, respectively, while mecA/SCCmec V was positive in only one isolate harboring solely tarJ. arcC and rpoB were classified into 14 and 10 allelic types, respectively. PSMβ consisted of 3, 4, or 6 units of 44 amino acid-peptide, forming eight different profiles. Both virulence factors nsr and tarJ were detected in 5 isolates (6 %), among which two isolates had the same PSMβ profile and arcC-rpoB types as those of the NRCS-A clone prototype strain CR01. The mecA-positive isolate was classified into the same arcC-rpoB lineage as that of CR01.
Conclusion:
The present study revealed that SCCmec-negative S. capitis with nsr/tarJ (proto-NRCS-A clone) is distributed at low prevalence to healthy individuals in Japan. These isolates belonged to arcC-rpoB lineages close to that of the NRCS-A clone.
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