Determining resistance profiles of staphylococci strains that isolated from clinical samples

Methicillin resistance of clinical isolates Staphylococcus aureus and coagulase negative staphylococci was planned to be detected by oxacillin and cefoxitine disk diffusion tests and mecA gene which is responsible for the resistance by polymerase chain reaction.150 staphylococcus strains isolated which clinic samples thatcomes from medical microbiology laboratory in Afyon Kocatepe Univercity between november 2009 ? 2010 april and the suspected methiciline resistance strains are tested. mecA gene which is accepted as gold standard was tested by polymerase chain reaction.In the oxacillin disk diffusion test, 52% of the Staphylococcus aureus and 91,1% of the CoNS isolates, in the cefoxitine disk diffusion test 53,1% of the Staphylococcus aureus and 93,3% of the CoNS isolates were found to be resistant. We isolated 45 CoNS strains and were identified 66,7% S.epidermidis, 31,1% S.hominis and 2,2% S.haemolyticus. It was found that one of MRSA strains were resis¬tant to linezolide.Detection of methicillin resistance in staphylococci by phenotypical methods often leads to false results. This problem is more evident in the CoNS than the Staphylococcus aureus isolates. In our study, Staphylococcus aureus isolates the results of the phenotypical methods, oxaciilin (sensitivity 98,6% and spesificity 100%) and cefoxitine disk diffusion tests (sensitivity 100% and spesificity 99,2%) were found to be consistent. CoNS isolates the results of the phenotypical methods, oxaciilin (sensitivity 95,3% and spesificity 100%) and cefoxitine disk diffusion tests (sensitivity 97,6% and spesificity 100%) were found to be consistent. However, the most appropriate method for detecting the methicillin resistance for both Staphylococcus aureus and CoNS isolates is detection of mecA gene by polymerase chain reaction.