Background: Bacterial skin infections in companion animals, particularly those involving multidrug-resistant Pseudomonas aeruginosa and methicillin-resistant Staphylococcus, pose significant therapeutic challenges due to rising resistance and biofilm formation. While Piper betle is well-recognized in human medicine, data on its efficacy against veterinary isolates—and the comparative phytochemistry and potency of its extracts versus essential oils—remains scarce. Objective: This study evaluated the antimicrobial and antibiofilm efficacy of an ethanolic P. betle leaf extract compared to a panel of representative essential oils—including P. betle leaf oil, clove, tea tree, and plai—against 73 feline and canine clinical isolates. Methods: Minimum inhibitory (MIC) and bactericidal (MBC) concentrations were determined via broth microdilution. Biofilm inhibition was assessed using crystal violet staining to determine the minimum biofilm inhibitory concentration (MBIC). Phytochemical profiles were characterized using gas chromatography–mass spectrometry (GC–MS) and liquid chromatography–quadrupole time-of-flight mass spectrometry (LC–MS/MS-QTOF). Results: P. betle leaf extract exhibited superior anti-pseudomonad activity (mean MIC: 1.5 mg/mL; MBC: 1.9 mg/mL), demonstrating significantly greater potency than the tested essential oils. Among the essential oils, clove oil was the most effective against Staphylococcus strains (mean MIC: 0.8 mg/mL; MBC: 1.2 mg/mL). Despite 74.4% of P. aeruginosa and 90.0% of Staphylococcus spp. being strong biofilm producers, the P. betle extract demonstrated the highest inhibitory potency against P. aeruginosa (MBIC: 0.7 mg/mL) and, alongside clove oil, showed superior efficacy against Staphylococcus spp. (MBICs: 0.3 and 0.7 mg/mL, respectively). GC–MS analysis identified chavibetol (confirmed via standard spiking) and hydroxychavicol as the primary extract constituents. LC–MS/MS-QTOF profiling further revealed a prominent phenolic profile, including 2,3-dihydroxybenzoic acid and 3,4-dihydroxybenzaldehyde. Comparative analysis suggests that while clove oil efficacy is primarily driven by high eugenol content, the broad-spectrum potency of the P. betle extract arises from a complex phenolic richness, specifically the synergistic presence of hydroxychavicol and chavibetol. Conclusions: These findings confirm the robust potential of P. betle extract as a promising plant-based antiseptic for managing biofilm-associated infections and mitigating antimicrobial resistance in veterinary medicine.
Soonthoranun et al. (Fri,) studied this question.