Recognition of major methicillin-resistant Staphylococcus aureus (MRSA) clones by molecular surveillance in Srinagarind Hospital, Khon Kaen

Abstract

Methicillin-resistant Staphylococcus aureus, a well-known nosocomial pathogen in tertiary healthcare facilities, can cause severe life-threatening symptoms. Nowadays, prevention and control of outbreaks related to hospital-acquired infections need molecular information to distinguish and definitely define a real etiology. For the last decade, molecular techniques have been developed and applied to an epidemiological study of infectious diseases. Among them, polymerase chain reaction-based typing techniques are most feasible to be used as molecular tools in clinical microbiology laboratory in Thailand. In this study, PCR-based typing methods, including SCCmec typing, variable numbers of tandem repeats typing of hypervariable region downstream of mecA (HVR) locus and spa gene, were applied in order to determine genetic background, and major endemic clones in Srinagarind Hospital, Khon Kaen. A total of 247 MRSA isolated from 124 patients of Srinagarind Hospital during July 2007 through December 2008 were characterized by the PCR-based typing methods described above. Five SCCmec types were identified as type-III (60.7%), type-IIIA (30.8%), type-II SCCmec (6%), type-III DCS (1.7%), and type-I variant with class C mec complex (0.9%), respectively. HVR and spa typing differentiated MRSA into 5 and 10 groups, respectively. Combination of all genetic markers could identify two major clones, III-15-7 (43.6%), and IIIA-7-7 (22.2%). Medical wards and medical intensive care unit were considered as endemic areas of these two clones. Information in this study may be applied to infection control measure and lead to development of suitable PCR-typing techniques for MRSA in clinical laboratory.