Molecular fingerprinting of meticillin-resistant Staphylococcus aureus strains isolated from patients and staff of two Iranian hospitals

Meticillin-resistant Staphylococcus aureus (MRSA) is an important cause of hospital-acquired infection. Methods for typing and epidemiological investigation of MRSA isolates have an important impact in detection of MRSA strains, source, transmission and control of these micro-organisms. The aims of this study were to study molecular diversity of MRSA isolates by randomly amplified polymorphic DNA (RAPD)-polymerase chain reaction (PCR), the surveillance efficacy of this method and determination of antibiotic resistance patterns of MRSA isolates. MRSA isolates were collected from clinical specimens and noses of 460 staff and inpatients admitted to Imam Khomeini and Paediatric Hospitals during a six-month period (2004-2005). Eighty MRSA strains, in which the presence of mecA gene had been confirmed by PCR, were subjected to RAPD-PCR using five primers and the results were summarised in a dendrogram to show the relationships between the test isolates. Antibiotic resistance patterns of MRSA isolates were also determined by disc agar diffusion method using 13 antibiotic discs according to Clinical and Laboratory Standards Institute guidelines. Forty-three RAPD-PCR profiles were detected. The test isolates were clustered into 18 taxa with 50% similarity, indicating the heterogeneity of our test isolates. MRSA isolates fell into 41 antibiotic resistance patterns. There was correlation between antibiotic resistance patterns and results of RAPD-PCR. Most of the MRSA isolates were multi-resistant.