Methicillin-resistant Staphylococcus aureus (MRSA) continues to be a global problem in infection control. The highest proportions of MRSA are reported by Jordan, Egypt and Cyprus investigators, where more than 50% of the invasive isolates are methicillin-resistant. The aim of this work was to study the prevalence, antibiotic sensitivity and genetic discrimination of MRSA in Egypt. Microbiological identification was done using Gram stain, catalase, coagulase and mannitol fermentation along with biochemical identification by analytical profile index (API) tests. Molecular identification was conducted by the polymerase chain reaction (PCR) targeting 16S ribosomal RNA and the nuc genes. Additionally, identification of methicillin-resistant S. aureus (MRSA) was performed by the amplification of 310 bp of the mecA gene. Antibiograms were performed for all isolates. Only 73 isolates out of 166 were oxacillin resistant. The percentage of resistant isolates to erythromycin, rifampicin, vancomycin, Ofloxacin, gentamycin, Amoxicillin clavulanic acid, ciprofloxacin, chloramphenicol, trimethoprim sulfamethoxazole, teicoplanin and tetracycline were 58, 32.50, 2.4, 45.18, 37.9, 39.7, 23.5, 21.6, 40.3, 0 and 39.1%, respectively. MRSA isolates were subdivided into eight biotypes according to their resistance pattern. Random amplification of polymorphic DNA (RAPD) and repetitive sequence DNA (REP) were performed on samples representing each biotype.
Key words: Methicillin-resistant Staphylococcus aureus (MRSA), nuclease, mecA, 16S rRNA, random amplified polymorphic DNA (RAPD), polymerase chain reaction (PCR).