Epidemiological Analysis of Methicillin-Resistant Staphylococcus aureus Strains Isolated From Hospital Infections by Using Arbitrarily Primed-Polymerase Chain Reaction (AP-PCR)

After 6 months surveillance of nosocomial infections at Dr. Siyami Ersek Cardiothoracic Surgery Center between December 1st 1995 to May 1st 1996, it was found that 39% (24/61) of nosocomial and 64% (18/28) of surgical site infections were caused by MRSA. The overall percentage of MRSA among all Staphylococcus aureus strains were found to be 62.5% (45/72) during the study period and antimicrobial susceptibility patterns were similar with each other in 89% (40/45) of these MRSA strains. To identify the potential sources of MRSA infections in this institution, nasal swab cultures of health care workers (HCW) were taken and the nasal colonization rate was found to be 2.8% (5/173). The strains that were isolated from patients and HCW’s were evaluated by AP-PCR. It was found that 75% (33/45) of the patient strains were similar with each other. One of the five strains isolated from HCW’s was similar with these strains. Although nasal colonization of that HCW had been treated effectively with mupirocin, MRSA infection rate wasn’t decreased at this hospital. Since MRSA carriage rate was not high in HCW’s and, most of the MRSA strains isolated from HCW’s were found to be different in genetic type from the patients’ strains, for the transmission of MRSA, it was concluded that nasal colonization of HCW’s with MRSA is not a major source of infections in our hospital