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Background: Preoperative bathing with chlorhexidine gluconate (CHG) is commonly practiced as a preventive measure to reduce the risk of postoperative surgical site infections (SSIs). Inadequate application of CHG could reduce the effectiveness of CHG in the prevention of SSIs. However, there are no commonly available methods to monitor the effectiveness of CHG application.
Objective: To evaluate the use of a simple colorimetric assay for detection of CHG on skin of patients receiving preoperative CHG bathing.
Methods: We performed a prospective observational study of 35 patients receiving preoperative bathing with 4% CHG rinse-off solution (N =25) or no-rinse 2% CHG cloths (N =10). On the morning of surgery, patients were interviewed to determine frequency, timing, and adequacy of bathing. Sterile swabs were applied to skin sites (neck, chest, abdomen, arm, and leg) and levels of CHG were assessed using a colorimetric assay. For comparison, levels of CHG were measured in the morning on skin of healthy volunteers who bathed with CHG once in the evening.
Results: Healthy volunteers consistently had detectable CHG on skin, but levels were higher for no-rinse cloths (range, 256 to 2,048 µg per swab) than rinse-off solution (range, 2 to 256 µg per swab) (P<0.001). Of 35 patients, 25 (71%) bathed with 4% CHG rinse-off solution (median number of applications, 1; range, 1 to >5) and 10 (29%) bathed once in the evening using no-rinse cloths. For no-rinse cloths, CHG was detected on all skin sites. Bathing with 4% rinse-off solution resulted in inconsistent detection of CHG on skin (77% of sites positive), and some patients had no detectable CHG on skin despite reporting adequate bathing.
Conclusions: A colorimetric assay for CHG could provide a simple and rapid method to monitor the effectiveness of CHG application after preoperative bathing.