Cooperativity between antibiotics and antiseptics: testing the bactericidal effect.

OBJECTIVE: Treatment with antibiotics together with local application of antiseptics is common in wound care. We investigated the effectiveness of an antiseptic in two variations: octenidine (Oct) and octenidine+ (Oct+ with isotonic glucose addition). METHOD: Using the agar diffusion test with cultures of pathogenic Staphylococcus aureus and the non-pathogenic Bordetella petrii, we compared the effectiveness of octenidine to the classical antiseptics beta-isodona (povidone-iodine; PI), chlorhexidine (Chl) and taurolin (Tau) alone, and in combination with various common antibiotics to uncover cooperativity between antiseptics and antibiotics. RESULTS: We detected strong interactions between antibiotics and antiseptics, that either enhanced or reduced the bactericidal efficiency. Effectiveness was dependent on the type of organism tested. Oct applied together with ineffective antibiotics frequently led to effective growth inhibition of Bordetella petrii. With Staphylococcus aureus we did not find such an effect. To this end, we reason that positively charged Oct may associate with antibiotic compounds via electrostatic interactions and guide it more efficiently to the bacterial cell wall. Interaction with antibiotics sometimes led to sequestration and reduced availability of some antiseptic/antibiotic combinations, but never with Oct. CONCLUSION: These data provide new arguments for decision planning concerning the choice of agent in the treatment of wound infections.

Cell growth and migration under octenidine-antiseptic treatment.

OBJECTIVE: The toxicity of octenidine antiseptics in cultured cells contrasts their good tolerability in tissue. This phenomenon prompted us to examine which cell culture conditions allow survival and proliferation and to investigate a possible modulation of toxicity by the extracellular matrix proteoglycan chondroitin sulfate. METHOD: We tested fibroblasts and MCF7 cells for growth using the MTT test, and assessed wound healing potency with a laceration assay. Expression levels of the genes involved in controlling wound healing were assessed with RT-PCR. RESULTS: A 24 hour exposure to the octenidine-based solution was found incompatible with cell growth. When octenidine solution (0.5-0.5mg/l) was coated on dishes, growth was profoundly reduced after 24 hours, however there was no cytotoxic effect at 0.012 mg/l. Interestingly, when dishes were first coated with chondroitin sulfate the cytotoxicity of octenidine-based solution was modulated. Cell migration was not inhibited by octenidine-based solution treatment (2 minutes; 15 mg/l). No significant changes in gene expression levels in response to the octenidine-based solution treatment were detected. CONCLUSION: In cell culture conditions application of the octenidine-based solution without toxicity can be observed, comparable to the minimal application required to give full bactericidal effect. Alteration of toxicity by interaction with chondroitin sulfate in cell culture suggests a similar function for extraceullar matrix in intact tissue.