Comparison of decontamination methods for human skin grafts

Skin grafts intended for autologous transplant may be dropped on the operating room floor during handling. The authors examined optimal procedures for decontaminating tissue intended for burn surgery. Porcine skin (5 × 5 cm sections) harvested from expired animals using standard procedures was inoculated with either 10⁶ CFU/ml Staphylococcus aureus or Klebsiella pneumoniae. Decontaminating strategies were compared: 10% povidone iodine, 0.04% chlorhexidine, or 50 U/ml bacitracin for injection, and mechanical agitation using normal saline or sterile water; each agent was applied for 60 seconds. Each skin section was blended and plated on agar for bacterial enumeration using the spread plate method. Tissue viability was evaluated in parallel using a cell viability reagent, along with a control (heat at 200°C for 5 min). Bacterial counts were log transformed; one-way ANOVA with Tukey-Kramer HSD analysis were performed. Concentration of organisms <10⁵ CFU/g was considered clinically insignificant colonization. Eight donors provided 21 S. aureus and six K. pneumoniae samples. After exposure, mean organism concentration (CFU/g) was <10⁵ for povidone iodine (S. aureus 2.83 × 10⁴; K. pneumoniae 1.85 × 10⁴), chlorhexidine (S. aureus 4.52 × 10⁴; K. pneumoniae 1.77 × 10⁴), and normal saline (K. pneumoniae 8.76 × 10⁴) treated groups. After log transform, only povidone iodine and chlorhexidine were found to be different from control in both groups. Viability was decreased in the positive control group, but not in treatment groups. Agents routinely used for surgical skin prep (povidone iodine and chlorhexidine), reduced both Gram-positive and Gram-negative contamination in tissue intended for skin grafting procedures. Antiseptic treatments did not impair the cellular viability of porcine skin.