Investigation of Methicillin Resistance of Staphylococcus aureus Strains Isolated from Various Sources by Different Methods

Object of this study is to determine methicillin resistance of 150 strains of Staphylococcus aureus isolated and identified from various sources by the methods of oxacillin agar screen, broth microdilution and oxacillin disc diffusion, to compare sensitivity and specificity of these methods by making oxacillin agar screen test reference and to determine multi-antibiotic resistance in these strains. 16 (10.7%) of the 150 strains were determined as Methicillin-Resistant S.aureus (MRSA) through the methods of agar screen and microdilution while 17 (11.3%) strains were found as the same through the method of disc diffusion. Agar screen and microdilution methods were found as 100% compatible with each other. Sensitivity of the disc diffusion method was calculated as 100% while its specificity was calculated as 99.2%. Antibiotic susceptibility tests conducted by using the disc diffusion method against 10 antibiotics showed that the highest resistances of MRSA and MSSA (Methicillin-Susceptible S. aureus) strains were determined as 100% and 93.3% to penicillin, 81.2% and 5.2% to tetracycline, 62.5% and 1.5% to ofloxacin, 56.2% and 0.7% to rifampin respectively while all strains were found susceptible to linezolid and vancomycin. It was seen that multiple-antibiotic resistance in MRSA strains are higher compared with that in MSSA strains. It has been thought that linezolid may be an alternative for vancomycin in curing MRSA infections.