Semiquantitative culture of open surgical wounds for diagnosis of surgical site infection.

The aim of this study was to assess the performance of a semiquantitative culture method and traditional qualitative culture for the diagnosis of surgical site infections resulting in an open wound. Results were correlated with the definitions for the diagnosis of SSI proposed by the Centers for Disease Control and Prevention, Atlanta, Ga., USA. The sensitivity, specificity, positive and negative predictive values of the qualitative culture method were 96%, 61%, 84% and 89%, respectively. For the semiquantitative technique with a breakpoint of 15 colony forming units/plate these values were 91%, 96%, 98% and 83%, respectively. Analysis of the receiver operating characteristic curve revealed an area under the curve of 94.44% (95% confidence interval, 88.5%-99%) for the semiquantitative method. This result indicates that our easy-to-perform semiquantitative culture technique for open surgical wounds correlates better with the diagnosis of SSI than the traditional qualitative method.