Evaluation of the Antimicrobial Activity of a 3% Chlorhexidine/Ophytrium Mousse and Shampoo in 18 Healthy Dogs

BACKGROUND: Topical antimicrobial therapy is vital for managing pyoderma yet poor compliance can affect treatment outcomes. HYPOTHESIS/OBJECTIVE: To evaluate the antimicrobial activity of a 3% chlorhexidine/ophytrium shampoo at different contact times and the residual activity of a 3% chlorhexidine/ophytrium mousse against meticillin-susceptible and -resistant Staphylococcus pseudintermedius (MSSP and MRSP), Escherichia coli (EC), ESBL-producing E. coli (ESBL), Pseudomonas aeruginosa (PA), and Malassezia pachydermatis (MP) in vitro. ANIMALS: 18 privately owned dogs. MATERIALS AND METHODS: Dogs were treated once with the shampoo for 3, 5 and 10 min, with hair samples taken after rinsing. The mousse was applied once. Hair samples were collected at 30 min (Day [D]0) and at D2, D4, D7 and D14 post-treatment. Hair bundles were plated on Mueller-Hinton (MH) agar plates pre-inoculated with MSSP, MRSP, EC, ESBL and PA, and on supplemented MH plates pre-inoculated with MP. Zones of inhibition (ZIs) were measured after 24 h (bacteria) and 48 h (MP) incubation. RESULTS: Shampoo-there were no significant differences in antimicrobial activity between the contact times for any of the isolates. Mousse-for all the isolates, there was significant growth inhibition compared to the negative controls on D0, D2 and D4. CONCLUSIONS AND CLINICAL RELEVANCE: Hairs exposed to the shampoo and mousse inhibited growth of all the isolates in vitro. A 3 min contact time was noninferior to 10 min for the shampoo. The mousse showed residual activity for ≥ 4 days for MSSP, MRSP, EC, PA and MP.