Quantitative culture technique and infection in complex wounds of the extremities closed with free flaps

The purpose of this study was twofold: (1) to determine if there is a relationship between a critical quantity of bacteria and infection in complex extremity wounds, and (2) to compare the positive and negative predictive values, sensitivities, and specificities of the following laboratory and clinical tests of potential wound infections: quantitative cultures, swab cultures, mechanism of injury, severity of fracture, and wound position. Fifty patients were evaluated who had 50 free-tissue transfers. Twenty-eight patients had quantitative cultures prior to flap coverage. All 50 patients were evaluated for wound position, presence or absence of a fracture, and mechanism of injury; 16 patients had swab cultures. The best positive predictive value (89 percent) and negative predictive value (95 percent), along with sensitivity (89 percent) and specificity (95 percent), for predicting wound infection were those of quantitative cultures. This demonstrates that in the clinical setting of this study, the test with the highest utility and validity is quantitative cultures.