Molecular Genotyping of Methicillin Resistant Staphylococcus aureus in Khartoum Teaching Hospital

Abstract

This is a cross—sectional study perfomied to detect the methicillin resistant Staphylococcus aureus (MRSA) isolates collected from Khartoum Teaching Hospital in the period from September 2005 to August 2007 by various molecular typing methods. A total of 48 S. aureus isolates were collected fiom clinical wound specimens in wards of surgery, orthopaedic, and burns. The number of MRSA was found to be 9 (l8.75%). The isolates were classified into 3 groups; group 1: S. aureus isolated from the surgical ward (28; 58.3%), group H: S. aureus isolated from the orthopaedic ward (14; 29.2%), and group IH: S. aureus isolated from the bums unit (6; 12.5%). All strains were studied for their susceptibility to commonly used antibiotics. The results revealed that the drug of choice for the treatment of nosocomial MRSA and MSSA is vancomycin. While multi-drug resistance was observed to be common among MRSA strains. Polymerase chain reaction (PCR) was used to amplify the sequence of S. aureus specific gene at (107 bp) all isolates. Methicillirt resistant (mec/1) gene yielded the amplicon for size at 1319 bp of 9 isolates, and coagulase (coa) gene produced amplification products approximately at 500 bp (26/48), and sso bp (22/48). Two distinct PCR-restriction fragment length polymorphism (RFLP) pattems of coagulase gene exhibited among isolates of S. aureus; coaA and coaB. With Alul restriction enzyme digested, the product fragments were approximately at 190, 310 bp and 190, 390 bp with percentages of 54.2% (26/48) and 45.8% (22/48) respectively.