A Staphylococcus xylosus Isolate with a New mecC Allotype

Abstract

jRecently, a novel variant of mecA known as mecC (mecA LGA251 ) was identified in Staphylococcus aureus isolates from both humans and animals. In this study, we identified a Staphylococcus xylosus isolate that harbors a new allotype of the mecC gene, mecC1. Whole-genome sequencing revealed that mecC1 forms part of a class E mec complex (mecI-mecR1-mecC1-blaZ) located at the orfX locus as part of a likely staphylococcal cassette chromosome mec element (SCCmec) remnant, which also contains a number of other genes present on the type XI SCCmec. Methicillin resistance in staphylococci is encoded by mecA, encoding the penicillin-binding protein 2a (PBP2a), which has a low affinity for beta-lactam antibiotics (1). As a result, the transpeptidase activity of PBP2a is functional at normally inhibitory concentrations of beta-lactam antibiotics, allowing cell wall synthesis to occur (2-4). Recently, a novel variant of mecA was identified in Staphylococcus aureus from cattle (5), humans, and a range of other animal species (6) in Denmark, France, The Netherlands, Ireland, Germany, Belgium, and the United Kingdom (5, 7-11). This subtype was originally designated mecA LGA251 but has since been renamed mecC and shares 70% nucleotide identity with the conventional mecA gene. The mecC gene is present with its cognate regulators mecI-mecR1, as part of a class E mec complex that shares structural similarity (mecI-mecR1-mecC-blaZ) with a mec gene complex found in Macrococcus caseolyticus (12). The class E complex is present as part of a larger, 29.4-kb, type XI staphylococcal cassette chromosome mec element (SCCmec) inserted at orfX; this element also includes the recombinase genes ccrAB and arsenic resistance genes. In this work, we describe a highly related mecC homolog present in the orfX locus in a Staphylococcus xylosus.A search of the EMBL nucleotide database identified submission of sequences from S. xylosus strain S04009 (13) with a high degree of similarity (Ͼ90%) to mecC (5, 8). However, antimicrobial susceptibility testing of strain S04009 by disk diffusion with oxacillin and cefoxitin showed it to be susceptible to both antibiotics but resistant to penicillin using British Society for Antimicrobial Chemotherapy (BSAC) criteria (version 10.2) (data not shown). Therefore, we submitted the mecC-positive strain S04009 and a mecC-negative S. xylosus isolate, S040010, for whole-genome sequencing to further characterize the mecC-containing region. Illumina library preparation was carried out as described by Quail et al. (14), and HiSeq sequencing was carried out following the manufacturer's standard protocols (Illumina, Inc.). Genome sequencing confirmed the presence of a mecC homolog in S04009 located downstream of the S. xylosus orfX homolog, a region associated with horizontally transferred elements (Fig. 1). Immediately downstream of orfX in S04009 is a 3.3-kb region that shows a high degree of similarity (Ͼ95% nucleotide identity) to the 3= end of the arginine catabolic mobile element (ACME) in the S. aureus USA300 strai...

Antimicrobial susceptibility profile and research of mec A and erm genes in coagulase-negative staphylococci isolated from platelet concentrates bags

“…This mecC gene has also been reported in CoNS as Staphylococcus stepanovicii, Staphylococcus xylosus and Staphylcoccus scirui (Harrison et al, 2013a(Harrison et al, , 2013bLoncaric et al, 2013). As already suggested for the mecA gene, we can probably infer that the origin of the mecC gene is also among the CoNS (Tsubakishita et al, 2010;Couto et al, 2013).…”

First Staphylococcal Cassette Chromosome mec Containing a mecB -Carrying Gene Complex Independent of Transposon Tn 6045 in a Macrococcus caseolyticus Isolate from a Canine Infection

“…The phylogenetic relationships of one representative of each type of ccr gene (19) and the mec gene complexes containing the blaZ gene (5)(6)(7)20) were investigated by the construction of a maximum likelihood phylogenetic tree using the SeaView program, version 4.4.0 (21), with nucleotide sequences deposited in the ENA/GenBank databases. Sequences were aligned using MUSCLE, and the trees were built with PhyML using a general time-reversible (GTR) model.…”

Adjunctive mecA PCR for Routine Detection of Methicillin Susceptibility in Clinical Isolates of Coagulase-Negative Staphylococci

“…The mecA homologue mecC has a reported prevalence rate of 0.5% for MRSA and has recently been reported in coagulase-negative staphylococcus (5,11,15,23). It is characterized by an oxacillin-resistant/cefoxitin-sensitive profile with Vitek II in S. aureus and a negative mecA PCR (15).…”

“…Although several studies have shown a close correlation between oxacillin resistance and the presence of the mecA gene (4,(8)(9)(10)(11)(12)(13)(14), changes in the epidemiology of resistance and the methodology of phenotypic tests necessitate ongoing appraisal of the role of routine sensitivity testing in the determination of beta-lactam resistance in coagulase-negative staphylococci.…”