Diagnosis of catheter-related infections: The role of surveillance and targeted quantitative skin cultures

The results of quantitative skin cultures have been proposed as predictors of central venous catheter infection. We prospectively observed 132 patients for 3 months after catheter insertion. Specimens were obtained from all patients for routine surveillance quantitative skin cultures. Targeted quantitative skin cultures and quantitative catheter cultures were done at the time of removal of the central venous catheter. At a positivity level of > 10³ colony-forming units per 24-cm² area of skin around the insertion site, the surveillance and targeted quantitative skin cultures had specificities and negative predictive values that exceeded 90%. However, they had sensitivities of 18% and 75%, respectively, and they had positive predictive values of 25% and 100%, respectively. Unlike surveillance quantitative skin cultures, targeted quantitative skin cultures that are done when catheter infection is suspected are highly sensitive, specific, and predictive.