Povidone-iodine ointment demonstrates in vitro efficacy against biofilm formation

Abstract

Anti-infectives used to treat chronic exuding wounds are diluted by wound exudates, absorbed into dressings, metabolised by proteases and destroyed by pH. In order to mimic such effects of exudates, the efficacy of six topical wound agents was assessed undiluted and at 10% concentrations, including povidone-iodine ointment and a silver-impregnated wound dressing, to remove biofilms of Pseudomonas aeruginosa, multi-species biofilms of Candida albicans and methicillin-resistant Staphylococcus aureus (MRSA) in vitro in a Centers for Disease Control and Prevention (CDC) reactor. Povidone-iodine was also diluted to 3·3% and 33·3% of the commercial concentrations. Viable microorganisms in each preparation were quantified by colony count. No viable P. aeruginosa biofilm material was recovered after 4 and 24 hours of treatment with povidone-iodine ointment at the 100% and 10% concentrations. No C. albicans/MRSA biofilm material was recovered after 4 and 24 hours of treatment with povidone-iodine ointment at the 100% concentration. In general, following dilution, povidone-iodine ointment appeared to exhibit greater biofilm removal than the other agents tested. Further research involving different microorganisms in vitro and in vivo over a longer period of time will help elucidate the full potential of povidone-iodine ointment and liposomal hydrogel.

Keywords: Biofilm; Candida albicans; Methicillin-resistant Staphylococcus aureus (MRSA); Povidone-iodine ointment (PVP-I); Pseudomonas aeruginosa.

Figure 1

Quantity of viable Pseudomonas aeruginosa recovered from coupons following 4‐hour treatment with all agents, at the commercial concentrations (100%) and at 10% of the commercial concentration. Silver dressing was tested at 100% only. MUP, mupirocin; FUA, fusidic acid; BNP, bacitracin, neomycin, and polymyxin B; PHB, polyhexanide/betaine; OCT, octenidine dihydrochloride; PVP‐I, povidone‐iodine ointment; PVP‐ILH, PVP‐I liposomal hydrogel; CHG, chlorhexidine gluconate; PBS, phosphate buffer solution.

Figure 2

Quantity of viable Pseudomonas aeruginosa recovered from coupons after 24‐hour treatment with all agents, at the commercial concentrations (100%) and at 10% of the commercial concentration. Silver dressing was tested at 100% only. MUP, mupirocin; FUA, fusidic acid; BNP, bacitracin, neomycin, and polymyxin B; PHB, polyhexanide/betaine; OCT, octenidine dihydrochloride; PVP‐I, povidone‐iodine ointment; PVP‐ILH, PVP‐I liposomal hydrogel; CHG, chlorhexidine gluconate; PBS, phosphate buffer solution.

Figure 3

Quantity of viable Candida albicans/MRSA recovered from coupons following 4‐hour treatment with all agents, at the commercial concentrations (100%) and at 10% of the commercial concentration. Silver dressing was tested at 100% only. The 33% and 3·3% concentrations of PVP‐I are also presented. MRSA, methicillin‐resistant Staphylococcus aureus; MUP, mupirocin; FUA, fusidic acid; BNP, bacitracin, neomycin, and polymyxin B; PHB, polyhexanide/betaine; OCT, octenidine dihydrochloride; PVP‐I, povidone‐iodine ointment; PVP‐ILH, PVP‐I liposomal hydrogel; CHG, chlorhexidine gluconate; PBS, phosphate buffer solution.

Figure 4

Quantity of viable Candida albicans/MRSA recovered from coupons after 24‐hour treatment with all agents, at the commercial concentrations (100%) and at 10% of the commercial concentration. Silver dressing was tested at 100% only. The 33% and 3·3% concentrations of PVP‐I are also presented. MRSA, methicillin‐resistant Staphylococcus aureus; MUP, mupirocin; FUA, fusidic acid; BNP, bacitracin, neomycin, and polymyxin B; PHB, polyhexanide/betaine; OCT, octenidine dihydrochloride; PVP‐I, povidone‐iodine ointment; PVP‐ILH, PVP‐I liposomal hydrogel; CG, chlorhexidine gluconate; PBS, phosphate buffer solution.

Figure 5

Quantity of viable Candida albicans/MRSA recovered from coupons after 4‐hour treatment with PVP‐I at standard concentration and different percentage concentrations. PVP‐I, povidone‐iodine ointment.

Figure 6

Quantity of viable Candida albicans/MRSA recovered from coupons after 24‐hour treatment with PVP‐I at standard concentration and different percentage concentrations. PVP‐I: povidone‐iodine ointment.