Summary auto-generated
This study describes a novel subspecies of Staphylococcus hominis, designated S. hominis subsp. novobiosepticus, isolated from human blood cultures, wounds, abscesses, and catheter tips between 1989 and 1996. Based on analysis of 26 strains, researchers used DNA-DNA reassociation reactions, macrorestriction pattern analysis, and phenotypic characterization to demonstrate that these isolates are genetically distinct from previously recognized S. hominis strains from human skin. The new subspecies is distinguished by combined resistance to novobiocin and inability to produce acid aerobically from D-trehalose and N-acetyl-D-glucosamine. All 26 strains exhibited extensive antibiotic resistance, including resistance to nalidixic acid, penicillin G, oxacillin, kanamycin, and streptomycin, with most also resistant to erythromycin, clindamycin, chloramphenicol, and ciprofloxacin. Analysis of the mecA gene identified homologue A, commonly found in other methicillin-resistant staphylococci. The type strain ATCC 700236T was designated as the reference strain. This represents the first novobiocin-resistant member of the S. epidermidis species group.
Key findings
- S. hominis subsp. novobiosepticus is a genetically distinct subspecies characterized by novobiocin resistance and inability to ferment trehalose and N-acetyl-D-glucosamine, differentiating it from S. hominis subsp. hominis
- All 26 strains displayed extensive multi-drug resistance including resistance to penicillin G, oxacillin, streptomycin, and nalidixic acid, with most also resistant to macrolides and fluoroquinolones
- The mecA gene present in this subspecies is homologue A, the same variant found in S. aureus and other coagulase-negative staphylococci
- SmaI-digest macrorestriction patterns and DNA-DNA hybridization confirmed this subspecies is significantly diverged from other S. hominis populations but represents a relatively recent clonal expansion
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Abstract
A new subspecies, Staphylococcus hominis subsp. novobiosepticus, isolated from human blood cultures, a wound, a breast abscess and a catheter tip, is described on the basis of a study of 26 strains isolated between 1989 and 1996. DNA-DNA reassociation reactions, conducted under stringent conditions, and macrorestriction pattern analysis demonstrated that these strains are closely related to previously characterized S. hominis strains isolated from human skin and clinical specimens, but are significantly divergent. S. hominis subsp. novobiosepticus can be distinguished from S. hominis (now named S. hominis subsp. hominis) by its combined characteristics of novobiocin resistance and failure to produce acid aerobically from D-trehalose and N-acetyl-D-glucosamine. Furthermore, all 26 strains of the new subspecies are resistant to nalidixic acid, penicillin G, oxacillin, kanamycin and streptomycin, and were either resistant or had intermediate resistance to methicillin and gentamicin. Most strains were also resistant to erythromycin, clindamycin, chloramphenicol, trimethoprim/sulfamethoxazole and ciprofloxacin. Based on a comparison of the sequences of a 1001 bp mecA amplification product from reference methicillin-resistant staphylococci, the mecA gene present in S. hominis subsp. novobiosepticus was identified as homologue A, commonly found in S. aureus and many coagulase-negative staphylococcal species. The type strain of S. hominis subsp. novobiosepticus is ATCC 700236T. Descriptions of S. hominis subsp. novobiosepticus subsp. nov. and S. hominis subsp. hominis are given and the description of S. hominis is emended.