Relationship between skin microbial counts and surgical site infection after neurosurgery

A prospective study was performed to describe the density of bacterial counts on the skin of neurosurgical patients and examine the association between total colony-forming unit (cfu) counts of skin flora at the operative site and surgical site infection (SSI). Two skin cultures were obtained, immediately before and after skin preparation, from the operative sites of 609 neurosurgical patients. SSI surveillance that used Centers for Disease Control/National Nosocomial Infection Surveillance definitions was performed. Predictors for high bacterial counts and SSI among craniotomies were analyzed by means of logistic regression. Neither pre- nor postpreparation counts were associated with SSI. Other SSI risk factors were obesity (relative risk [RR], 2.5), duration of surgery (RR, 1.3 for every additional 30 minutes) and age (RR, 0.7 for each additional 10 years). Duration of skin preparation was not correlated with postpreparation cfu counts. We were unable to detect an association between preoperative bacterial skin counts and SSI.