Change in the molecular epidemiology of methicillin-resistant Staphylococcus aureus bloodstream infections in Taiwan ☆ Chih-Jung Chen a,c , Po-Ren Hsueh e , Lin-Hui Su b,d , Cheng-Hsun Chiu a,d , Tzou-Yien Lin a,d , Yhu-Chering Huang a,d, ⁎ a Divisions of Pediatric Infectious Diseases, Department of Pediatrics, Chang Gung Children's Hospital, 333, Taoyuan, Taiwan b Department of Clinical Pathology, Chang Gung Memorial Hospital, Taoyuan, Taiwan c Graduate Institute of Clinical Medical Science, College of Medicine, Chang Gung University, 333, Taoyuan, Taiwan d Pediatric Research Center, Chang Gung Memorial Hospital, Taoyuan, 333, Taiwan e Department of Laboratory Medicine, National Taiwan University Hospital, 100, Taipei, Taiwan Received 1 February 2009; accepted 29 May 2009 Abstract A multiresistant community-associated methicillin-resistant Staphylococcus aureus clone (sequence type 59) established itself as a significant cause of nosocomial bloodstream infections soon after emergence in the communities. Multiresistance might be one of the characteristics that could have contributed to its quick adaptation to hospital environments. © 2009 Elsevier Inc. All rights reserved. Keywords: Methicillin-resistant Staphylococcus aureus; Community-associated infections; Bloodstream infections; Taiwan Methicillin-resistant Staphylococcus aureus (MRSA) that met the epidemiologic definition for community-associated (CA) infection was first documented in Taiwan in 1997 and identified in 9.8% to 36% of all childhood CA S. aureus infections between 1997 and 2001 (Chen et al., 2005a; Wang et al., 2004). The rate rapidly increased to 56% during 2004 and 2005 (Huang et al., 2008). Genotypic analysis demon- strated that a clone (ST59, defined by multilocus sequence typing [MLST]) carrying a SCCmec IV or V T element and expressing multiresistance to non–β-lactams (including erythromycin and clindamycin) was responsible for the major outbreaks of CA-MRSA infections in this island (Lo et al., 2006; Wang et al., 2004). Further, the ST59 clone caused a substantial proportion of health care-associated (HA)-MRSA infections in a children's hospital during 2000 and 2001 (Chen et al., 2005a, 2005b). The finding suggested that the multiresistant CA-MRSA clone might have spread into the hospitals soon after its emergence in the communities. To better understand the change in epidemiology of MRSA infections in the health care facilities and estimate the magnitude of the multiresistant CA-MRSA clone in causing serous nosocomial infections in Taiwan, we conducted a longitudinal study by comparing the antibiograms and molecular features of 257 MRSA blood isolates collected from 1995 to 2006 in the National Taiwan University Hospital, Taipei, Taiwan. The 257 isolates comprised the first 10% of consecutive and nonduplicate MRSA blood- stream infections (BSIs) isolates in each year of the study. Community-onset MRSA was defined as isolates from bloodstreams obtained within 48 h of admission, whereas HA-MRSA was defined as those from bloodstreams obtained beyond that time. Susceptibilities to various antibiotics (Table 2) were determined with disc diffusion methods according to the guidelines set forth by Clinical and Laboratory Standards Institute. The pulsed-field gel electro- phoresis (PFGE) of SmaI digests of chromosomal DNAs and SCCmec typing was according to previously described methods (Huang et al., 2004). MLST was performed for representative strains of each major PFGE type according to Available online at www.sciencedirect.com Diagnostic Microbiology and Infectious Disease 65 (2009) 199 – 201 www.elsevier.com/locate/diagmicrobio ☆ The study was supported by a grant from Chang Gung Memorial Hospital (CMRPG450122). ⁎ Corresponding author. Division of Pediatric Infectious diseases, Department of Pediatrics, Chang Gung Memorial Hospital, Taoyuan 333, Taiwan. Tel.: +886-3-3281200; fax: +886-3-3288957. E-mail address: ychuang@adm.cgmh.org.tw (Y.-C. Huang). 0732-8893/$ – see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.diagmicrobio.2009.05.020