Efficacy of skin preparation in eradicating organisms before total knee arthroplasty.

The solution of 2% chlorhexidine gluconate and 70% isopropyl alcohol (Chloraprep) is commonly used for antiseptic skin preparation before surgery. We conducted a study to evaluate the efficacy of this solution in eradicating organisms during skin preparation for total knee arthroplasty (TKA), to isolate the organism type, and to evaluate possible contributing factors leading to infection. Ninety-nine patients who were undergoing TKA were swabbed for cultures in the popliteal fossa before and after solution application. Swabs were collected, cultured, and read. Culture isolates grew in 20 (20%) of the 99 patients before solution application and in 5 (5%) of the 99 after application. Mean presolution body mass index (BMI) was 38 for patients with bacterial isolates and 34 for patients without isolates (P<.03). Mean postsolution BMI was 40 for patients with bacterial isolates and 35 for patients without isolates. BMI was a statistically significant factor in predicting presence of isolates after solution application. In addition, presence of bacteria in presolution cultures was predictive of isolation in postsolution cultures. Diabetic patients were 3.6 times more likely than nondiabetic patients to have a bacterial isolate. Other factors did not predict organism isolation. No patient developed a postoperative infection.