Molecular Epidemiologic Analysis of Methicillin-Resistant Staphylococcus aureus using Pulsed-Field Gel Electrophoresis / 대한임상병리학회지

ABSTRACT

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen that is frequently involved in outbreaks of nosocomial infections. We did moleculoepidemiological analysis of MRSA strains isolated at the Dongsan Medical Center from January 1998 to June 1998 by means of a pulsed-field gel electrophoresis (PFGE) and antimicrobial resistance phenotyping. METHODS: One hundred six strains of MRSA, isolated from patients, were analyzed and classified by DNA fingerprinting with PFGE by CHEF-DR III (Bio-Rad Co., USA) after digestion with SmaI. An antimicrobial sensitivity test was performed and the patterns were compared to the PFGE patterns. RESULTS: Among the 106 isolates, 28 different PFGE patterns were identified. Nineteen patterns were responsible for more than one strain (2 to 24 strains). Twenty-seven patterns showed over 65% in the similarity coefficient and were classified into 8 groups (I-VIII). Group II strains were mostly isolated from wound and sputum, whereas group III from pleural fluid and urine. Most of group II isolates were from patients of the wards (40% of NS isolates, 71% of OS isolates and 60% of IM isolates) and ICUs (50% of SICU and MICU isolates). The antibiogram separated the isolates into 11 types. Type 6 was predominant and subdivided into groups II, III and VII of the PFGE patterns. CONCLUSIONS: Molecular chromosomal DNA fingerprinting with PFGE revealed the clonal relationships of some MRSA isolates at the Dongsan Medical Center. Thus, molecular epidemiological analysis with PFGE would be valuable for delineating epidemic isolates of MRSA, for identifying the nosocomial reservoirs, and for tracing their intrahospital spread.