Evaluation of phenotypic and genotypic methods for detection of methicillin - resistant Staphylococcus aureus strains

Food-borne pathogenic is a group of micro -organis ms that caus e food -borne illnes s thus , the res earch for finding effective drugs agains t this infection is neces s ary. Staphylococcus aureus is the major caus e of food -borne and nos ocomial infection in las t decade and methicillin res is tant S. aureus (MRSA) has emerged as a major clinical problem. The aim of the pres ent s tudy was to compare different phenotypic methods with genotypic method by polymeras e chain reaction (PCR) for the detection of MRSA s trains . Sens itivity to methicillin was als o inves tigated by oxacillin, methicillin, cefotetan, cefoxitin, cefmetazole dis ks , the data tab, and dis k diffus ion method and oxacillin s trip. Minimum inhibitory concentration (MIC) of thes e is olates was determined by us ing micro-broth dilution. A total of 186 is olates of S. aureus with PCR method (gold s tandard) were detected. About 95 is olates were methicillin -s ens itive S. aureus , and 91 is olates were MRSA. Among the diagnos tic methods s tudied, micro - broth dilution and cefoxitin dis k had the mos t s pecificity with 98.9% and 94.7%, res pectively. The s ens itivity of them was 100.0% and 98.9%, res pectively. Furthermore, the concordance with PCR was 98.9% and 93.6%, res pectively. The cefotetan and cefmetazole dis ks had the lowes t concordance with the res ults of PCR. Due to the neces s ity of us ing s imple, reliable and low-cos t methods in routine diagnos tic laboratories it s eems us e of cefoxitin dis k s till be cons idered as one of recommended methods for detecting MRSA is olates.