In Vitro Antimicrobial Activity of Piper betle Leaf Extract and Some Topical Agents against Methicillin-Resistant and Methicillin-Susceptible Staphylococcus Strains from Canine Pyoderma

SIMPLE SUMMARY: Pyoderma is one of the most common diseases in dogs. The primary pathogen isolated from canine pyoderma is Staphylococcus pseudintermedius, followed by Staphylococcus schleiferi subsp. coagulans. With the emergence of a multidrug-resistant strain, namely, methicillin-resistant staphylococci (MRS), topical antimicrobial therapy is encouraged. In this study, the in vitro antimicrobial activity of crude Piper betle leaf extract and some topical antimicrobials against clinical S. pseudintermedius and S. schleiferi subsp. coagulans, including their MRS strains, were evaluated. It was found that betel leaf extract demonstrated good antimicrobial activity with a higher proficiency than azelaic acid and benzoyl peroxide. Accordingly, betel leaf extract could provide a novel antimicrobial treatment, which may help reduce the need for systemic antibiotics, for canine pyoderma. ABSTRACT: As multidrug-resistant methicillin-resistant staphylococci (MRS) is becoming more prevalent in canine pyoderma, the discovery of new therapeutic options is required. This study aimed to test the antimicrobial activity of crude Piper betle leaf extract and some topical antimicrobial agents against canine Staphylococcus clinical strains by determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The results showed that the mean MICs of chlorhexidine, miconazole, crude P. betle leaf extract, azelaic acid, and benzoyl peroxide against Staphylococcus strains were 1.41, 1.62, 252.78, 963.49, and 1342.70 mg/L, respectively. Therefore, betel leaf extract demonstrated a superior efficacy to azelaic acid and benzoyl peroxide. Furthermore, the ratio of MBC/MIC of betel leaf extract was 1.75, indicating its bactericidal action. When applied to methicillin-resistant S. pseudintermedius (MRSP) and methicillin-susceptible S. pseudintermedius (MSSP), betel leaf extract was equally efficient towards both groups. S. pseudintermedius strains were more susceptible to betel leaf extract than S. schleiferi subsp. coagulans. In gas chromatography–mass spectrometry analysis, eugenol and hydroxychavicol appeared to be the major components of betel leaf extract. Given its efficacy, dogs with pyoderma could benefit from the use of betel leaf extract as a topical antimicrobial alternative.