Rapid diagnosis of methicillin-resistant Staphylococcus aureus bacteremia by nested polymerase chain reaction

Objective: The purpose of this study was to establish a rapid and sensitive diagnostic method for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia in postoperative patients. Summary Background Data: As a result of diffusion and abuse of third-generation cephalosporin antibiotics in the 1980s in Japan, an outbreak of MRSA infection has been posed. In the field of surgery, severe postoperative infections with MRSA such as MRSA bacteremia, which may lead to multiple organ failure, have emerged with a high mortality. Methods: Thirty-five patients with high fever (above 38.5°C) or watery diarrhea or both within 2 weeks after gastrointestinal major surgery and 6 healthy volunteers were examined. Nested polymerase chain reaction was used to detect meca and toxic shock syndrome toxin-1 (TSST-1) genes in blood specimens. Results: The meca and TSST-1 genes were not detected in the blood samples of any of the six healthy volunteers. In all 12 samples from which MRSA colonies were isolated by blood culture, mecA and TSST-1 genes were detected. Although it took at least 48 hours to identify MRSA by the blood culture method, the presence of mecA and TSST-1 genes was determined by nested polymerase chain reaction method within only 3 to 4 hours after blood sampling. Conclusions: This method, as a sensitive and rapid monitoring system for MRSA bacteremia, would be clinically beneficial for prevention of cross infection and for early determination of appropriate treatment for infected patients.