P‐8 Antibacterial efficacy of 0.1% chitosan solution against Staphylococcus intermedius in dogs

Abstract

Antibacterial efficacy of 0.1% chitosan solution against Staphylococcus intermedius in dogs was determined by the modified detergent scrub quantitative technique in 10 adult mongrel dogs. For comparison, other antibacterial agents including 2.5% benzoyl peroxide, 0.5% chlorhexidine acetate, 0.1% chitosan solution combined with 2.5% benzoyl peroxide, and chitosan combined with 0.5% chlorhexidine were used. The antibacterial activity of chitosan was inversely affected by pH with higher activity at lower pH value and exerted the highest activity at pH 4.5 in vitro. In nontreated bacteria‐challenged control sites, S. intermedius was found to have counts of 6.95 ± 0.53 cfu/cm2 of skin. The counts of recovered Staphylococcus intermedius (cfu/cm2) from the treated sites were 3.25 ± 0.98 for 0.1% chitosan solution, 0.68 ± 1.13 for benzoyl peroxide, 3.14 ± 0.55 for chlorhexidine, 0.48 ± 0.56 for chitosan solution combined with benzoyl peroxide, and 2.55 ± 0.88 for chitosan solution combined with chlorhexidine. Each S. intermedius recovery value from the five treated sites was significantly (P < 0.01) lower than that from the nontreated bacterial‐challenged control site. The 0.1% chitosan solution was efficacious against Staphylococcus intermedius in dogs. However, the combinations of chitosan with benzoyl peroxide and with chlorhexidine were shown to exert higher activity when compared to those of chitosan alone and benzoyl peroxide or chlorhexidine alone. Thus, 0.1% chitosan solution was considered to have antibacterial activity against Staphylococcus intermedius andhave potential for clinical applications in the treatment of pyoderma in dogs. Funding: Self‐funded.