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 the 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 was 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. The 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 a 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.

Background:One of the most challenging isolates in nosocomial infections is Acinetobacter baumannii which is rapidly changing towards multi-drug resistant. Resistance to the last resort antibiotics, carbapenems, is reported around the world. In particular, metallo-β-lactamases (MBL) are responsible and detection of MBLs is of interest. Objectives: In this study we have evaluated the prevalence of MBLs in A. baumannii isolated during 2012 by two feasible described methods. Materials and Methods:In this cross sectional study, during 2012, 40 A. baumannii non-replicate isolates gathered from clinical and environmental specimens from Afzalipur hospital of Kerman. Isolates were characterized by conventional biochemical tests as A. baumannii-calcoaceticus complex (ABC). For antimicrobial susceptibility testing, 17 different antibiotics were sought by agar diffusion method. Phenotypic MBL detection was assessed by double disk test and Modified Hodge test for carbapenem resistant isolates. Results: During the study 40 isolates of ABC were collected. Of which, 23 (57%) isolates were resistant to carbapenems. Phenotypic MBLs detection was negative by two methods. Conclusions:The rates of resistance of the isolated ABCs in our clinical setting were at high level. Though, carbapenems were the most efficient antibiotic, but, there was a pronounced rate of resistant. MBL genes were not responsible for carbapenem resistance in under study clinical setting.

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