Bacteriological and Molecular Studies of Methicillin-Resistant Staphylococcus aureus in Eastern province of Saudi Arabia

Methicilin (oxacilin) staphylococcus aureus (MRSA) constitutes a great challenge to many hospitals worldwide. A total of 110 MRSA isolate were collected from 110 patoents from five medical institution in Dammam. Qatif and Dhahran, Saudi Arabia. The ratio of male to female isolates were 2:1. All age groups were affected, the higher prevalence was detected in elderly patients. The highest frequency was found in ICUs followed by medical and surgical wards. The underlying diseases associated with MRSA colonization and infection includes uncontrolled chronic and subsequent diseases. Colonization of the nares represent the main carriage site. The main risk factors were long hospitalization period, intensive use of antibiotics, long stay in ICU and the underlying diseases. All the specimens were included onto MSA selective media, the organism identified following the NCCLS standard identification tests. MRSA identified phenotypically by growth on oxacilin screen plate and resistance to oxacilin (MIC > 256 ug/ml). Merhicilin resistance was confirmed genetically by 2 detection of MESA using PCR assay. 98.2% of the isolates were multiple drug resistant. Vancomycin intermediate or resistant stairs were not detected. Antibiogram typing classify the isolates into 31 patterns. The isolate relatechess was determined using PFGE. Comparison of DNA fingerprints identify a major clonal clusters. Persistently present in all hospitals involved. MLST revealed that genuine genetic was obscured by PFGE analysis. St 239 was very overrepresented among these isolates, where 97% share the ST 239 diversifies while maintaining its core genome intact. Apparently, we are faced with a high successful MRSA clones