Molecular epidemiology of hospital-onset methicillin-resistant Staphylococcus aureus infections in Southern Chile

GUSTAVO MEDINA; ANA L. EGEA; C. OTTH; L. OTTH; H. FERNÁNDEZ; BOCCO J.L; M. WILSON; CLAUDIA SOLA

EUROPEAN JOURNAL OF CLINICAL MICROBIOLOGY & INFECTIOUS DISEASES : OFFICIAL PUBLICATION OF THE EUROPEAN SOCIETY OF CLINICAL MICROBIOLOGY.

SPRINGER

Lugar: Berlin; Año: 2013 vol. 32 p. 1533 - 1540

0934-9723

Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogen of public health importance. In Chile, the Cordobes/Chilean clone was the predominant healthcare- associated MRSA (HA-MRSA) clone in 1998. Since then, the molecular epidemiological surveillance of MRSA has not been performed in Southern Chile.We aimed to investigate the molecular epidemiology of HA-MRSA infections in Southern Chile to identify the MRSA clones involved, and their evolu- tionary relationships with epidemic international MRSA line- ages. A total of 303 single inpatient isolates of S. aureus were collected in the Valdivia County Hospital (2007?2008), reveal- ing 33 % (100 MRSA/303) prevalence for HA-MRSA infec- tions. The SCCmec types I and IV were identified in 97 % and 3 % of HA-MRSA, respectively. All isolates lacked the pvl genes. A random sample (n = 29) of all MRSAwas studied by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), SCCmec subtyping, agr and spa typing, and virulence genes profiling. PFGE analysis revealed the predominance (89 %, 26/29) of pulsotype A and three additional pulsotypes, designated H1, I33, and G1. Pulsotype A (ST5-SCCmecI-spa-t149) is clonally related to the Cordobes/Chilean clone. Pulsotype H1 (ST5-SCC mecIVNT-spa-t002) is genetically related to the Pediatric clone(ST5-SCCmecIV). Pulsotype I33 (ST5-SCCmecIVc-spa-t002) is clonally related by PFGE to the community-associatedMRSA (CA-MRSA) clone spread in Argentina, I-ST5-IVa-PVL+ .The G1 pulsotype (ST8-SCCmecIVc-spa-t024) is clonally related to the epidemic USA300 CA-MRSA. Here, we demonstrate the stability of the Cordobes/Chilean clone over time as the major HA-MRSA clone in Southern Chile. The identification of two CA-MRSA clones might suggest that these clones have entered into the healthcare setting from the community. These results emphasize the importance of the local surveillance of MRSA infections in the community and hospital settings.