Wound contamination with endogenous bacterial scalp flora plays an important role in the pathogenesis of postoperative neurosurgical
infections. To assess the effect of preoperative
antiseptic shampoos on the emergence of resident scalp flora during surgery and subsequent
wound contamination, we randomized 151
neurosurgical procedures into four study groups: group A--preoperative shampoos with
chlorhexidine, surgical scalp preparation with
chlorhexidine; group B--no shampoos, surgical preparation with
chlorhexidine; group C--shampoos with iodophor, surgical preparation with iodophor; group D--no shampoos, surgical preparation with iodophor. Quantitative cultures of the scalp were obtained preoperatively and at the end of surgery, and qualitative
wound cultures were taken prior to
wound closure. Group A had the lowest concentration of bacteria on the scalp both preoperatively and postoperatively (median range = 30 [0-5.7 x 10(5)] and 0 [0-2.5 x 10(3)] respectively). Group A also had significantly fewer positive postoperative scalp cultures (29%) than groups B (
51%), C (58%), and
D (53%) (P less than 0.05), as well as fewer positive
wound cultures (20% v 25%, 42%, and 30% respectively). A density of bacteria on the scalp of greater than 10(2)/4cm2 best predicted the presence of bacteria in the
wound. Repeated preoperative shampoos with
chlorhexidine reduce intraoperative emergence of resident skin flora and subsequent contamination of the
wound.