Quantitative analysis of bacteria in forefoot surgery: a comparison of skin preparation techniques

Currently a lack of consensus exists on the optimum solution and preparation methods needed to decrease bacteria present during forefoot surgery. We therefore compared the effect of povidine-iodine and chlorhexidine gluconate on lowering bacterial load and to study any additional benefits gained by pre-treatment with the use of a bristled brush.

Fifty consecutive patients undergoing forefoot surgery were recruited into the study and randomized to receive one of two surgical skin preparations (Povidine-iodine 1% with isopropyl alcohol 23% or Chlorhexidine gluconate 0.5% with isopropyl alcohol 70%). In addition to the skin preparation of the foot with the randomized solution, the subjects other foot was also scrubbed with a sterile surgical bristled brush for three minutes and then painted with the same solution. Swabs were taken from three sites and analyzed via qualitative and quantitative analysis before and after prepping.

All four preparation methods significantly decreased (p < 0.001), in all three sites, the number of colony forming units. Using two-way analysis of variance, no significant interaction was observed between preparation method and number of colony-forming units, suggesting that no difference in bacterial inhibition between preparation methods.

We suggest that either povidone-iodine with no more that 23% isopropyl alcohol or chlorhexidine gluconate with 70% isopropyl alcohol be used for surgical preparation in forefoot surgery. No additional benefit in reduction in bacterial load was gained by scrubbing the foot with bristles prior to painting.