Abstract
ObjectivesmecC methicillin-resistant Staphylococcus aureus (MRSA) represent a newly recognized form of MRSA, distinguished by the possession of a divergent mecA homologue, mecC. The first isolate to be identified came from bovine milk, but there are few data on the prevalence of mecC MRSA among dairy cattle. The aim of this study was to conduct a prevalence study of mecC MRSA among dairy farms in Great Britain.MethodsTest farms were randomly selected by random order generation and bulk tank samples were tested for the presence of mecC MRSA by broth enrichment and plating onto chromogenic agar. All MRSA isolated were screened by PCR for mecA and mecC, and mecC MRSA were further characterized by multilocus sequence typing, spa typing and antimicrobial susceptibility testing.ResultsmecC MRSA were detected on 10 of 465 dairy farms sampled in England and Wales (prevalence 2.15%, 95% CI 1.17%–3.91%), but not from 625 farms sampled in Scotland (95% CI of prevalence 0%–0.61%). Seven isolates belonged to sequence type (ST) 425, while the other three belonged to clonal complex 130. Resistance to non-β-lactam antibiotics was uncommon. All 10 isolates produced a negative result by slide agglutination for penicillin-binding protein 2a. mecA MRSA ST398 was detected on one farm in England.ConclusionsmecC MRSA is widely distributed among dairy farms in Great Britain, but this distribution is not uniform across the whole country. These results provide an important baseline dataset to monitor the epidemiology of this emerging form of MRSA.
Highlights
Methicillin-resistant Staphylococcus aureus (MRSA) encoding a divergent mecA homologue within a novel SCCmec type XI element were first reported in bovine and human isolates from the UK, Denmark and Eire in 2011.1,2 Originally named mecALGA251, and subsequently designated mecC,[3] this homologue shares 69% nucleotide identity with mecA and produces a negative result in mecA-based PCR assays and slide agglutination tests for penicillin-binding protein (PBP) 2a.As a result of its recent discovery and these diagnostic difficulties, there are relatively few data on the prevalence and epidemiology of mecC MRSA
Given that the original mecC MRSA isolate was found in bovine milk and that S. aureus is an important cause of bovine mastitis,[20] we undertook a prevalence study of mecC MRSA in dairy bulk tank samples in Great Britain (GB) collected during
None of the positive farms was in Wales (n1⁄4 90), giving a prevalence of 0%, and providing a prevalence of 2.67% for the 375 dairy farms sampled in England. mecC MRSA-positive farms were found in five counties distributed from the south-west (Devon and Cornwall) to the north of England
Summary
Methicillin-resistant Staphylococcus aureus (MRSA) encoding a divergent mecA homologue within a novel SCCmec type XI element were first reported in bovine and human isolates from the UK, Denmark and Eire in 2011.1,2 Originally named mecALGA251, and subsequently designated mecC,[3] this homologue shares 69% nucleotide identity with mecA and produces a negative result in mecA-based PCR assays and slide agglutination tests for penicillin-binding protein (PBP) 2a.As a result of its recent discovery and these diagnostic difficulties, there are relatively few data on the prevalence and epidemiology of mecC MRSA. Methicillin-resistant Staphylococcus aureus (MRSA) encoding a divergent mecA homologue within a novel SCCmec type XI element were first reported in bovine and human isolates from the UK, Denmark and Eire in 2011.1,2 Originally named mecALGA251, and subsequently designated mecC,[3] this homologue shares 69% nucleotide identity with mecA and produces a negative result in mecA-based PCR assays and slide agglutination tests for penicillin-binding protein (PBP) 2a.
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