Prevalence and antibiotic susceptibility pattern of methicillin resistant Staphylococcus aureus at Armed Forces Hospital in Saudi Arabia.

Methicillin-resistant Staphylococcus aureus (MRSA) is well recognized as a major cause of nosocomial infections worldwide and is associated with high morbidity and mortality rates with rapid development of resistance. MRSA has become established outside the hospital environment and is now appearing in community populations without identifiable risk factors. The traditional treatment for infections caused by MRSA is vancomycin, which is indicated for treatment of antibioticassociated pseudomembranous colitis caused by Clostridium difficile. First described in 1944, penicillinase-producing strains of S. aureus became universally present in hospitals in the 1950s and dominant in the community in the early 1970s. Methicillin was introduced in 1959 as the first betalactamase-resistant penicillin, but outbreaks of MRSA infections were reported in Europe soon thereafter, and nosocomial MRSA strains are now distributed worldwide. MRSA organisms generally are resistant to multiple antibiotics, including aminoglycosides, macrolides, fluoroquinolones, clindamycin, trimethoprimsulfamethoxazole, chloramphenicol, and betalactams. Though vancomycin resistant S. aureus is not widely seen, a low level resistance to vancomycin is being reported. Hence, the knowledge of the prevalence of MRSA and their antimicrobial susceptibility pattern becomes necessary in the selection of appropriate empirical treatment.