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Extensive Genetic Diversity Identified among Sporadic Methicillin-Resistant Staphylococcus aureus Isolates Recovered in Irish Hospitals between 2000 and 2012

2014; American Society for Microbiology; Volume: 58; Issue: 4 Linguagem: Inglês

10.1128/aac.02653-13

1098-6596

Peter M. Kinnevey, Anna C. Shore, Gráinne I. Brennan, Derek J. Sullivan, Ralf Ehricht, Stefan Monecke, David C. Coleman,

Bacterial biofilms and quorum sensing

ABSTRACT Clonal replacement of predominant nosocomial methicillin-resistant Staphylococcus aureus (MRSA) strains has occurred several times in Ireland during the last 4 decades. However, little is known about sporadically occurring MRSA in Irish hospitals or in other countries. Eighty-eight representative pvl -negative sporadic MRSA isolates recovered in Irish hospitals between 2000 and 2012 were investigated. These yielded unusual pulsed-field gel electrophoresis and antibiogram-resistogram typing patterns distinct from those of the predominant nosocomial MRSA clone, ST22-MRSA-IV, during the study period. Isolates were characterized by spa typing and DNA microarray profiling for multilocus sequence type (MLST) clonal complex (CC) and/or sequence type (ST) and SCC mec type assignment, as well as for detection of virulence and antimicrobial resistance genes. Conventional PCR-based SCC mec subtyping was undertaken when necessary. Extensive diversity was detected, including 38 spa types, 13 MLST-CCs (including 18 STs among 62 isolates assigned to STs), and 25 SCC mec types (including 2 possible novel SCC mec elements and 7 possible novel SCC mec subtypes). Fifty-four MLST- spa -SCC mec type combinations were identified. Overall, 68.5% of isolates were assigned to nosocomial lineages, with ST8-t190-MRSA-IID/IIE ± SCC M1 predominating (17.4%), followed by CC779/ST779-t878-MRSA-ψSCC mec -SCC-SCC CRISPR (7.6%) and CC22/ST22-t032-MRSA-IVh (5.4%). Community-associated clones, including CC1-t127/t386/t2279-MRSA-IV, CC59-t216-MRSA-V, CC8-t008-MRSA-IVa, and CC5-t002/t242-MRSA-IV/V, and putative animal-associated clones, including CC130-t12399-MRSA-XI, ST8-t064-MRSA-IVa, ST398-t011-MRSA-IVa, and CC6-t701-MRSA-V, were also identified. In total, 53.3% and 47.8% of isolates harbored genes for resistance to two or more classes of antimicrobial agents and two or more mobile genetic element-encoded virulence-associated factors, respectively. Effective ongoing surveillance of sporadic nosocomial MRSA is warranted for early detection of emerging clones and reservoirs of virulence, resistance, and SCC mec genes.