Transfer of the methicillin resistance genomic island among staphylococci by conjugation

Summary Methicillin resistance creates a major obstacle for treatment of Staphylococcus aureus infections. The resistance gene, mecA, is carried on a large (20 kb to > 60 kb) genomic island, staphylococcal cassette chromosome mec (SCCmec), that excises from and inserts site‐specifically into the...

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Bibliographic Details
Published in:Molecular microbiology 2016-05, Vol.100 (4), p.675-685
Main Authors: Ray, M. D., Boundy, S., Archer, G. L.
Format: Article
Language:English
Subjects:
Antibiotics
Chromosomes, Bacterial
Conjugation, Genetic
DNA, Bacterial
Drug resistance
Genes
Genomic Islands
Gram-positive bacteria
Methicillin Resistance - genetics
Methicillin-Resistant Staphylococcus aureus - genetics
Plasmids
Staphylococcus aureus
Staphylococcus aureus - drug effects
Staphylococcus aureus - genetics
Staphylococcus epidermidis
Staphylococcus epidermidis - drug effects
Staphylococcus epidermidis - genetics
Staphylococcus infections
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Summary:Summary Methicillin resistance creates a major obstacle for treatment of Staphylococcus aureus infections. The resistance gene, mecA, is carried on a large (20 kb to > 60 kb) genomic island, staphylococcal cassette chromosome mec (SCCmec), that excises from and inserts site‐specifically into the staphylococcal chromosome. However, although SCCmec has been designated a mobile genetic element, a mechanism for its transfer has not been defined. Here we demonstrate the capture and conjugative transfer of excised SCCmec. SCCmec was captured on pGO400, a mupirocin‐resistant derivative of the pGO1/pSK41 staphylococcal conjugative plasmid lineage, and pGO400::SCCmec (pRM27) was transferred by filter‐mating into both homologous and heterologous S. aureus recipients representing a range of clonal complexes as well as S. epidermidis. The DNA sequence of pRM27 showed that SCCmec had been transferred in its entirety and that its capture had occurred by recombination between IS257/431 elements present on all SCCmec types and pGO1/pSK41 conjugative plasmids. The captured SCCmec excised from the plasmid and inserted site‐specifically into the chromosomal att site of both an isogenic S. aureus and a S. epidermidis recipient. These studies describe a means by which methicillin resistance can be environmentally disseminated and a novel mechanism, IS‐mediated recombination, for the capture and conjugative transfer of genomic islands. SCCmec, the genomic island containing the gene that encodes methicillin resistance, was captured on a conjugative plasmid by recombination at IS elements and transferred by conjugation between different Staphylococcus aureus sequence types and between S. aureus and Staphylococcus epidermidis. In some of the recipients SCCmec excised from the plasmid and inserted site‐specifically into the recipient chromosome. This is the first demonstration of a mechanism for the interspecies dissemination of methicillin resistance among staphylococci.
ISSN:0950-382X
1365-2958
DOI:10.1111/mmi.13340