Abstract

In this study, pulsed field gel electrophoresis (PFGE) was used for genomic DNA finger printings of methicillin-resistant Staphylococcus aureus (MRSA) isolates. Thirty strains  of S. aureus collected from major hospital laboratories and public health centers, Riyadh, King Saudi Arabia were tested phenotypically by conventional methods and genotypically by multiplex-PCR for direct detection of S. aureus 16S rRNA and mecA genes. The chromosomal DNA of the isolates was examined by using pulsed-field gel electrophoresis (PFGE) using SmaI. SmaI cut the chromosomal DNA of the examined MRSA into 9 to 13 fragments, moreover, 16 chromosomal digestion patterns were observed out of the 30 examined isolates. The first pulsed field gel electrophoresis (PFGE1) contains 9 strains recovered from soft tissue infections and surgical wound infections. The second one (PFGE 2) contains 4 MRSA isolates, 3 of which were recovered from skin and soft tissue infections, while one was recovered from wound infection. Moreover, there are 3 chromosomal digestion patterns (PFGE 3, 4 and 5), each pattern involved two strains of MRSA which were recovered from surgical wound infections. A dendrogram of percent similarity, revealed three major clusters, the first cluster containing four groups (17 strains). The second cluster contains one group (12 strains), while the third cluster contains only one strain recovered from deep abscess.

Key words: Fingerprinting, Staphylococcus aureus, pulsed field gel electrophoresis, nosocomial infection, multiplex-PCR.