In vitro cytotoxicity of antimicrobial agents to human keratinocytes

Backround The degree of bacterial contamination in the wound bed plays a key role in determining the level of “take” of keratinoeyte grafts in burn patients. This study was done to evaluate the best suited antimicrobial agent for topical application in relation to antimicrobial activity and cytotoxic effect on graft cells. Objective The cytotoxicity of 7 antibacterial agents (gentamicin sulphate, ciprofloxacin hydrochioride, bacitracin, polymyxin B sulphate, diethanolamin salt of fusidic acid, teicoplanin, vancomycin hydrochtoride), one anlifungal substance (amphotcricin B sodium deoxycholate) and one antiseptic agent (povidone iodine) on cultured human keratinocytes, HaCaT keratinocytes and fibroblasts was investigated. Material and methods The effects of these agents were tested using two separate assays - the neutral red assay and the Bradford protein assay. In order to assess toxicity of the agent, the obtained midpoint cytotoxicity (MC50) was compared to the respective minimal inhibitory concentration (MIC) for receiving the cytotoxic potential in microbiologically effective doses. Results Antibiotics effective against Staphylococcus aureus with a small potential of toxicity are Bacitracin, Fusidic acid, Vancomycin and Tcicoplanin. Gentamicin and Ciprofloxacin are effective against both Staphylococcus aureus and Pseudomonas aeruginosa with a low potential of toxicity. Conclusion The use of antimicrobial agents with a midpoint cytotoxicity (MC50) higher than the minimal inhibitory concentration (MIC) by at least a factor of 100 might reduce the risk of toxic injury to graft cells.