The determination of mecA gene presence in MRSA strains isolated from intensive care unit by conventional, automated and PCR method

Meticillin-resistant S. aureus (MRSA) strains are becoming increasingly important as a cause of hospital and community-acquired infections. The aim of this study is to compare PCR, gradient tests and automated system which are the methods for determining methicillin resistance in S. aureus strains. The study included 50 MRSA strains isolated from various samples (wound, blood, sputum, respiration, abscess, osteomyelitis, etc.) from the microbiology laboratory of Van Yüzüncü Yil University Medical Faculty between 2010-2016. A single isolate was obtained from each patient. In our study, the presence of mecA gene in MRSA strains was investigated by conventional, automated and PCR methods. The presence of methicillin resistance was found in 49 of 50 MRSA strains which were examined by Oxacillin E-test method (MIC>2). All of the strains which were tested by cefoxitin E-test were found resistant to methicillin (MIC>4). Vitek 2 automated system detected that all of the strains are resistant to methicillin. All samples examined by PCR method were positive, the presence of mecA gene was determined. Sensitivity rate of strains examined by oxacillin E-test method was 98%, while the susceptibility rate of strains examined by cefoxitin E-test, Vitek 2 automated system and PCR methods was 100%. In order to obtain the necessary precautions in hospitals with high MRSA ratio, mecA investigation is of great importance in achieving the correct results. Since the results of the three methods are almost close to each other, three methods can be used to determine the correct results.