Methicillin resistance in coagulase-positive (CPN) staphylococci is a major threat to both, human and veterinary medicine. In recent years, the origin of the methicillin-resistance encoding gene mecA has been identified among coagulase-negative staphylococci (CNS) like Staphylococcus fleurettii, Staphylococcus vitulinus and further CNS. In 2011, a novel mecA homologue (mecC; EMBL FR821779) harbored by SC-CmecXI was described for MRSA from human and bovine origin, and later also from companion animals. We suspected that mecC, similar to mecA, originated potentially from CNS.
Material and methods:
The Staphylococcus stepanovicii strain IMT27065 (ODD4) was isolated in August 2011 from a fecal sample of a bank vole (Myodes glareolus) as part of a screening study focusing pathogens from wild rodents in Germany (Network “Rodent-Borne Pathogens”). Rectal swabs were enriched for staphylococcal growth in order to prevent overgrowing gram-negative bacteria. The staphylococcal species of isolate IMT27065 was verified by 16S rRNA sequence analysis (LGC Genomics, Berlin). A positive PCR-result for mecC was the reason for sequencing the whole genome of the strain on a HiSeq (Il-lumina, USA). The reads were assembled us ing CLC Genomics Workbench 6.5 (CLC bio, Denmark) and genomic comparative analyses were performed using Geneious 6.1.5 (Biomaters, New Zealand).
The mecC gene of IMT27065 (EMBL: KC110686.1) shares 99.2% nucleotide and 98.5% amino acid sequence identity with the mecCLGA251 of the recently described SCCmecXI in Staphy-lococcus aureus. Furthermore, the surrounding region revealed the presence of genomic elements similar to those of the class E mec of SCCmecXI (blaZ, mecC, mecR1, mecI) and the presence of the arsenic resistance operon.
Here we present S. stepanovicii as potential origin of the mecC gene and the class E mec in SCCmecXI. Further compara tive genomic analysis including more regions surrounding mecC genes harbored by CNS are needed to reconstruct the phylogeny of
SCCmecXI in S. aureus. Our data highlights the role of the environmental resistome as an important source of antibiotic resistance in op- portunistic bacteria such as S. aureus.
- ASM 113th (2013)