Determination of Antibiotic Resistance Profile and Frequency of Metallo-Beta- Lactamases in Pseudomonas Aeruginosa Isolates

Pseudomonas aeruginosa is an opportunistic pathogen and one of the most frequent pathogens in nosocomial infections. This bacterium shows high resistance to majority of antibiotics including â-lactams. The aim of this study was to investigate the pattern of antimicrobial resistance and evaluation of IMP, SPM and SIM Metallo- Beta- Lactamase producing Pseudomonas aeruginosa, in clinical samples isolated from Zanjan hospitals, by phenotypic and PCR methods. In this cross-sectional study, 120 Pseudomonas aeruginosa isolates were collected from the various clinical specimens in Zanjan hospitals from 2013 to 2014. After identification of isolates using biochemical tests, the antibiotic susceptibility test (Kirby-Baur method) was done according to CLSI advice against 7 antibiotics. The Combined Disk method was then carried out for detection of MBLs and the blaIMP, blaSPM and blaSIM genes were determined by a PCR method. In this study, Cefotaxime and Amikacin with 43.3% and 21.6% showed the highest and lowest resistance against isolates, respectively. From a total of 120 isolates, 35 (29.2%) strains were imipenem resistant and metallo- beta-lactamase producer. From 35 MBL producing isolates, 28 (80%) strains, 20 (57.1%) strains and 5 (14.3%) strains carried blaIMP, blaSPM and blaSIM genes, respectively and 1 (2.8%) isolate carried all blaIMP, blaSPM and blaSIM genes. According to the results, high prevalence of resistance to aztreonam and imipenem can be a warning against treatment process and distribution of resistance to other strains.