Preoperative disinfection of foot and ankle: microbiological evaluation of two disinfection methods

Background: The aim of the current study was to investigate the effect of a footbath in alcohol prior to preoperative disinfection on bacterial flora of the foot and ankle. Methods: Twenty-two volunteers underwent skin preparation mimicking pre-surgical disinfection. One foot was submerged in a bag filled with 70% ethanol containing 10% IPA for 5 min after which it was painted with regular 0.5% chlorhexidine in 70% alcohol. The other foot was only painted with 0.5% chlorhexidine in 70% alcohol. Swabs were taken at four locations: (1) under the nailfold of the first toe, (2) first webspace, (3) sinus tarsi and (4) pre-tibial. A quantitative and qualitative analysis of the cultures was performed. Results: No statistically significant difference between the number of positive cultures between the two methods was observed. The number of colony forming units was statistically significantly lower on two locations in the footbath group (i.e., subungual and the first webspace) (median 1 versus median 92 p =0.03 and median 0 versus median 1 p =0.03, respectively). The number of cultures with heavy growth was lower in the footbath group under the nailfold of the first toe (5 versus 13 p =0.008). Thirty-eight different microorganisms were cultured. Conclusion: A footbath in alcohol prior to regular preoperative skin antisepsis significantly reduces the amount of bacteria under the nailfold and in the first webspace. The number of cultures with heavy growth is lower after a footbath in alcohol. Level of evidence: IV.