Molecular typing of methicilin-resistant Staphylococcus aureus isolates atAin ShamsUniversityHospital

Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen and it has been increasingly seen in community settings. The general objective of this study was to characterize by phenotyping and genotyping methods MRSA strains isolated from inpatients, outpatients and health care workers. Specimens were collected from patients in Ain Shams University hospitals. Genotyping is based on polymerase chain reaction (PCR) and restriction fragment-length polymorphism (RFLP), following Hae II digestion of the amplified part of the hyper variable region of mecA gene (mecA- HVR). The study included 51 phenotypically detected MRSA isolates by conventional methods. PCR revealed the presence of 50 mecA positive strains, whereas, one strain was genotypically mecA negative. PCR-RFLP revealed three different patterns (A, B and C) which were detected in the three tested groups in patients – outpatients and health care workers (HCWs) in variable percentages. Genotyping using PCR-RFLP of mecA-HVR can rapidly demonstrate and discriminate the relatedness of isolates in different hospital wards and also in the community. As the same genotypes (A, B and C) of MRSA were detected in both hospitals and communities as well as in HCWs, therefore it is impossible to decide where they originated. Key words: Methicillin-resistant Staphylococcus aureus, polymerase chain reaction, hospital acquired