Efficacy of chlorhexidine, polihexanide and tissue-tolerable plasma against Pseudomonas aeruginosa biofilms grown on polystyrene and silicone materials.

BACKGROUND The formation of biofilms is crucial in the pathogenesis of many acute and subacute microbial infections, including chronic wounds and foreign-body-related infections. Topical antimicrobial therapy with chemical antiseptics or physical treatment with tissue-tolerable plasma (TTP) may be promising to control bacterial infection. METHODS We assessed the efficacy of 0.1% chlorhexidine digluconate (CHX), 0.02 and 0.04% polihexanide (polyhexamethylene biguanide, PHMB) and of TTP against Pseudomonas aeruginosa SG81 biofilm grown in microtitre plates (polystyrene) and on silicone materials in an artificial wound fluid. RESULTS Overall, PHMB was as effective as CHX in reducing the total amount of biofilm (gentian violet assay) and in reducing the bacterial metabolism in biofilms (XTT assay). TTP also led to a significant reduction in colony-forming units. CONCLUSION The antimicrobial activity of PHMB in biofilms is comparable to that of CHX. TTP could become an interesting physical alternative to chemical antisepsis in the future.