Resistance to Antimicrobial Agents, Chemical Disinfectants and Distribution of Effectors Proteins of Type Three Secretion System in Pseudomonas aeruginosa Isolated From Burn and Hospital Environments in South East of Iran

Pseudomonas aeruginosa (P. aeruginosa) is a common bacteria associated with burn infections and resistance to a wide range of disinfectants and antimicrobial agents which is able to produce different virulence factors. In this study, the susceptibility of P. aeruginosa isolates from burn (burn=57) and hospital environment (HE=19) to antimicrobial agents and chemical disinfectants was determined by disc and well diffusion agar method, respectively. The results showed 100% sensitivity to polymyxin B, while sensitivity to other agents were low and ranged from 40.8% for imipenem and amikacin to 6.6% for ceftizoxime. Among the disinfectant used the mean diameter of inhibition zones (DIZ) was higher for deconex while nitrofurazone had the lowest DIZ. In most cases the HE isolates were significantly more susceptible to disinfectants and antimicrobial agents compared to burn isolates (P≤0.01). The genes for the exoenzyme T, Y, U and S were detected in 100%, 89.8%, 43.4% and 48.7% of the isolates respectively. Prevalence of exo U and exoY was significantly higher in the burn isolates compared to HE isolates (P=0.001). The results of this study indicate significantly higher level of resistance against the majority of the antimicrobial agents in the burn isolates compared to HE isolates which was significantly higher than the environmental isolates. The prevalence of T3SS effectors proteins and their pattern were also different in the burn and the HE isolates, indicating a divergence in pathogenicity of the burn isolates from those of the environmental isolates.