The In Vitro Antibacterial Effects of Genipin Against Pathogens Commonly Associated With Infected Ulcerative Keratitis: A Canine Preliminary Study

PURPOSE: To evaluate genipin as a novel antimicrobial therapeutic agent with established crosslinking abilities by investigating its antibacterial activity against canine ocular pathogens and exploring its pharmacodynamic profile.

METHODS: Nineteen bacterial strains were selected from frozen stock, including ten Staphylococcus pseudintermedius (five of which were methicillin-resistant [MRSP]), five Pseudomonas aeruginosa, and four Streptococcus canis. All strains were isolated from dogs with corneal stromal ulcerations. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were examined; subsequently, time-kill assays were performed. Viability counts were performed at 0, 10, 30, 60, and 120 minutes.

RESULTS: Blue discoloration of the contents in the wells impeded the determination of the MIC values for all pathogens. MBC values ranged from 0.1% for MRSP, 0.075%-0.125% for S. pseudintermedius and P. aeruginosa, and 0.25%-0.5% for S. canis. Time-kill analysis demonstrated a mean bacteriostatic effect of genipin against staphylococci at 1 × MBC after 120 minutes, and a mean bactericidal effect after 120 minutes at 2.5 × MBC and after 60 minutes at 5 × MBC. No antibacterial effect was measured for P. aeruginosa within the tested timeframe and genipin concentrations.

CONCLUSIONS: Genipin exhibited promising antibacterial activity against all tested isolates, including MRSP. We suggest that genipin acts as a concentration-dependent antimicrobial agent, demonstrating bactericidal activity at higher concentrations against staphylococci. P. aeruginosa appeared less susceptible to the short-term effects of genipin. Further investigation is warranted to elucidate genipin's full antimicrobial potential and clinical performance.