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A novel hybrid SCCmec-mecC region in Staphylococcus sciuri.


Type

Article

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Authors

Harrison, Ewan M 
Paterson, Gavin K 
Holden, Matthew TG 
Rolo, Joana 

Abstract

OBJECTIVES: Methicillin resistance in Staphylococcus spp. results from the expression of an alternative penicillin-binding protein 2a (encoded by mecA) with a low affinity for β-lactam antibiotics. Recently, a novel variant of mecA known as mecC (formerly mecALGA251) was identified in Staphylococcus aureus isolates from both humans and animals. In this study, we identified two Staphylococcus sciuri subsp. carnaticus isolates from bovine infections that harbour three different mecA homologues: mecA, mecA1 and mecC. METHODS: We subjected the two isolates to whole-genome sequencing to further understand the genetic context of the mec-containing region. We also used PCR and RT-PCR to investigate the excision and expression of the SCCmec element and mec genes, respectively. RESULTS: Whole-genome sequencing revealed a novel hybrid SCCmec region at the orfX locus consisting of a class E mec complex (mecI-mecR1-mecC1-blaZ) located immediately downstream of a staphylococcal cassette chromosome mec (SCCmec) type VII element. A second SCCmec attL site (attL2), which was imperfect, was present downstream of the mecC region. PCR analysis of stationary-phase cultures showed that both the SCCmec type VII element and a hybrid SCCmec-mecC element were capable of excision from the genome and forming a circular intermediate. Transcriptional analysis showed that mecC and mecA, but not mecA1, were both expressed in liquid culture supplemented with oxacillin. CONCLUSIONS: Overall, this study further highlights that a range of staphylococcal species harbour the mecC gene and furthers the view that coagulase-negative staphylococci associated with animals may act as reservoirs of antibiotic resistance genes for more pathogenic staphylococcal species.

Description

Keywords

MRSA, mecA, β-lactams, Animals, Cattle, DNA, Bacterial, Gene Expression Profiling, Gene Order, Genes, Bacterial, Genome, Bacterial, Genotype, Molecular Sequence Data, Reverse Transcriptase Polymerase Chain Reaction, Sequence Analysis, DNA, Staphylococcal Infections, Staphylococcus

Journal Title

J Antimicrob Chemother

Conference Name

Journal ISSN

0305-7453
1460-2091

Volume Title

69

Publisher

Oxford University Press (OUP)
Sponsorship
Medical Research Council (G1001787)
This work was supported by a Medical Research Council Partnership Grant (G1001787/1) held between the Department of Veterinary Medicine, University of Cambridge (M. A. H.), the School of Clinical Medicine, University of Cambridge (S. J. P.), the Moredun Research Institute (R. N. Z.) and the Wellcome Trust Sanger Institute (J. P. and S. J. P.). S. J. P. receives support from the NIHR Cambridge Biomedical Research Centre. X. B. was supported by the China Scholarship Council and the Cambridge Overseas Trust. J. R. was supported by fellowship SFRH/BD/72675/2010 from Fundac¸a˜o para a Cieˆncia e a Tecnologia.