Isolation, Sensitivity, and Tolerance of Pseudomonas aeruginosa from Canine Otitis

Aims: This study aimed to detect Pseudomonas from cases of canine otitis and profile their antibiotic sensitivity pattern.

Study Design: We collected samples aseptically. Antibiogram was done by disc diffusion test. The broth microdilution method was applied for biocide tolerance against chlorhexidine (CHX) and Cetyl Trimethyl ammonium bromide (CTAB).

Place and Duration of Study: The study period was from March 2023 to March 2024. Samples(n=28) collected were by veterinarians treating the dogs presented at Teaching Veterinary Clinical Complex Pookode and Peripheral Veterinary Clinics, Kakkavayal, Wayanad District, Kerala, India and submitted to the laboratory.

Methodology: P. aeruginosa was identified based on colony characteristics and biochemical tests. Antibiotic sensitivity was estimated by a disc diffusion on Muller Hinton Agar. Broth microdilution assay for the minimum inhibitory concentration (MIC) of biocides was done in 250 ul plate and cation-adjusted Muller Hinton Broth for culturing bacterial isolates. Statistical analysis using Orange Machine Learning Software and Jamovi statistical application.

Results: Nine isolates of Pseudomonas aeruginosa were obtained. Ciprofloxacin was most effective against most isolates. The difference was statistically significant. Polymixin B and ceftriaxone-tazobactam had lower median zone sizes and were below the cut-off point for sensitivity. There was variation in the zone diameter for most of the drugs. The distribution of zone diameters was positively skewed for gentamicin, ceftriaxone-tazobactam, levofloxacin, ceftazidime, ciprofloxacin, and ofloxacin. Chlorhexidine had a statistically significant lower MIC than for CTAB.

Conclusion: Ciprofloxacin could be a better therapeutic option for treating canine otitis caused by P. aeruginosa. Better environmental sanitation against pathogenic Pseudomonas aeruginosa could be attained by chlorhexidine than CTAB.