Pseudomonas aeruginosa is an opportunistic pathogen of clinical significance in both human and veterinary medicine. In human healthcare, it is primarily associated with multidrug-resistant hospital-acquired infections. In companion animals, it commonly causes chronic and difficult-to-treat infections of the ears, wounds, and respiratory tract. This study aimed to evaluate the impact of sub-inhibitory concentrations of commonly used antiseptics in veterinary practice on the biofilm-forming ability of P. aeruginosa strains of animal origin. Ten P. aeruginosa strains of animal origin (dogs, cats) isolated from clinical samples as a primary cause of infection, were selected for analysis. Antibiotic susceptibility of the tested strains was determined using the disk diffusion method in accordance with EUCAST and CLSI guidelines. The minimum inhibitory concentrations for two antiseptics: Octenisept and Polisept Vet Wound Irrigation Silver Pro were determined using the microdilution method. Subsequently, the effects of 1/4 and 1/8 MIC concentrations on biofilm formation and its early structure were assessed. Additionally, we evaluated the impact of a short-term exposure to MIC concentrations of tested agents on mature P. aeruginosa biofilms. Fluorescence microscopy was employed to visualize differences in biofilm architecture after 48 h of exposure to the antiseptics in 1/4 MIC concentrations. All analyzed strains were resistant to amoxicillin–clavulanic acid, tetracycline, and trimethoprim/sulfamethoxazole. The minimum inhibitory concentration values were 0.00625% for Octenisept (Schülke however, the total number of cells differed substantially, with more than a twofold increase observed under the tested conditions. Sub-inhibitory concentrations of antiseptics were found to stimulate biofilm formation in P. aeruginosa strains. Given the potential for low concentrations of antiseptics to occur in the environment, further research and close monitoring of this phenomenon are necessary.
Foksiński et al. (Thu,) studied this question.