The treatment of methicillin resistant Staphylococcus aureus (MRSA) infection is challenging because of their high resistance to different antibiotics. The objectives of this study were to detect the prevelance of S. aureus and MRSA carriage in ICU patients in Al Quwayiyah General Hospital and to evaluate the performance of MRSA-Select agar media for rapid screening of MRSA Furthermore, to describe the antibiotic susceptibility patterns of the S. aureus and MRSA isolates. During the period from January to July 2018, a total of 278 patients admitted to the ICUs were screened for MRSA. Culture of specimens was done on, MRSA-Select agar plate, Oxacillin Screen Agar BD (Mueller-Hinton oxacillin agar screen plate containing 4% NaCl and oxacillin 6mg/ml) and blood agar. Suspected colonies of S. aureus were identified as by Gram stain, catalase, DNase, mannitol fermentation, and coagulase positivity or by Vitek2 ID-GP card. All strains were tested with Oxacillin disc diffusion method, Cefoxitin disc diffusion method, Latex agglutination test for detection of PBP2a and Susceptibility testing of oxacillin-susceptible mecA-positive isolates by the Vitek 2. The study showed that 56 (20.14%) isolates were MRSA, 45(16.18%) were MSSA, 164(58.99%) were CONS, 4 (1.44%) were Strept viridians, 2(0.71%) were gram negative bacteria, 3 (1.07%) were Corynebacterium spp., while 3 (1.07%) showed no growth. Antimicrobial susceptibility results for the MSSA and MRSA isolates showed that all MRSA isolates were totally resistant to β Ampicillin/sulbactam, Benzyle penicillin, Cefuroxime and Tetracycline while MSSA isolates susceptibilities to same antibiotics were 75%, 60%, 98.7% and 75% respectively. Susceptibility of MRSA to Quinupristin/dalfopristin, clindamycin, trimethoprim sulfamethoxazol, erythromycin, streptomycin were 98%, 72.4%, 65.6%, 55.4% and 63.8% respectively, while MSSA isolates showed more susceptibilities to same antibiotics which were 100%, 98.7%, 80.8%, 82.9 and 98.7% respectively. Both MRSA and MSSA isolates were 100% susceptible to levofloxacin, linzolide, Tigecycline, vancomycin. the sensitivity and specificity of diagnostic methods for MRSA by Oxacillin disc diffusion were 91.4% and 99.2% respectively, Cefoxitin disc diffusion were 98.5% and 99.2%, MRSA -select agar were 99.2% and 98.4% respectively, Oxacillin Screen Agar were 97.1% and 100% respectively and Latex agglutination were 100% and 99.2%. Risks of and infection episodes due to Staph. aureus were significantly different between MRSA carriers versus MSSA carriers and Colonization MRSA versus Other microorganisms. Total ICU acquired Staph. aureus infection were occurred in 7.14% MRSA carriers, 3.05% MSSA carriers and 1.03% Other micro organisms colonization. Conclusions: The prevalence of MRSA is high and rapidly increasing at Al Quwayiyah General Hospital, as it is worldwide. Control measures to prevent the spread of MRSA in hospital should continue with reinforcement of hygienic precautions and development of policies to restrict the use of antibiotics.

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