In vitro antimicrobial activity of a commercial dermatologic solution (PEPTIVET SOL.) containing chlorhexidine digluconate, Tris- EDTA and a novel antimicrobial peptide (AMP2041)

Cutaneous infections are frequently present in dogs due to bacteria and/or yeasts. The presence of new topical antimicrobials could help to reduce the use of systemic antibiotics and antifungal drugs. The aim of this study was to evaluate the in vitro antimicrobial activity of a commercial dermatologic solution (PEPTIVET SOL. ICF, Cremona, Italy) containing 0.02% chlorhexidine digluconate (CLX), Tris 0.4%, EDTA 0.1% and 0.5 lg/mL of antimicrobial peptide AMP2041 on bacterial and fungal reference strains involved in canine cutaneous infections. The dynamics of bacterial killing was evaluated with time-kill curves obtained with undiluted product incubated with the standardized suspensions of Escherichia coli ATCC25922, Pseudomonas aeruginosa ATCC27853, Proteus mirabilis ATCC14153, Staphylococcus aureus ATCC25923, MRSA ATCC43300, Staphylococcus pseudintermedius ATCC49444, Streptococcus canis ATCC20715, Malassezia pachydermatis ATCC14522 and Candida albicans ATCC10231. At fixed intervals (30 sec, 1, 5 & 10 min), 20 lL of suspension were plated for colony forming unit (CFU) counts. Time-kill assay obtained with the undiluted product showed complete microbicidal effect at 30 sec for E. coli, P. aeruginosa, S. canis, S. pseudintermedius and C. albicans reference strains. The fungicidal effect was complete at 1 min for M. pachydermatis ATCC14522, while for P. mirabilis, S. aureus, and MRSA reference strains a complete bactericidal effect was reached within 5 min. The undiluted product shows a very fast and complete antimicrobial activity against a panel of bacterial and fungal reference strains involved in canine cutaneous infections although clinical studies will be needed to evaluate the in vivo activity.