Frequency of Extended-Spectrum Beta-Lactamase (ESBLs) –Multidrug Resistance Produced by Pseudomonas aeruginosa Isolated from Clinical Specimens in Khorramabad City, Iran
Hossein Azizi
Department of Microbiology, Broujerd Branch, Islamic Azad University, Borujerd, Iran
Farnaz Kheirandish
Department of Parasitology and Mycology, Razi Herbal Medicines Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran
Mohsen Mirzaei *
Department of Microbiology, Broujerd Branch, Islamic Azad University, Borujerd, Iran
*Author to whom correspondence should be addressed.
Abstract
Background: Pseudomonas aeruginosa is one of the most important pathogenic bacteria causing hospital infections, which has intrinsic resistance to many antibiotics. One of the reasons for the emergence of drug resistance in P. aeruginosa isolates is the production of ESBLs (extended-spectrum beta-lactamase) enzymes. Resistance rate is increasing due to the production of these enzymes in P. aeruginosa. The goal of this study was to determine the prevalence of ESBL senzymes in P. aeruginosa isolates from different samples of patients in Khorramabad city by CDT (combined disk test) phenotypic method.
Methods: This study was an investigation on 70 P. aeruginosa samples isolated from patients in medical centers of Khorramabad city during one year (2013). The bacteria were identified by routine biochemical tests. Antibiotic sensitivity of the isolates was evaluated by double disk diffusion method. Phenotypic investigation of ESBLs production among the tested isolates using cefotaxime and ceftazidime disks alone and in combination with clavulanic acid (combined disk test) was performed.
Results: Results of combined disk test showed that, out of 70 isolated pseudomonas, 100% of the samples had multi-drug resistance. Maximum resistance to cefixime (79.1%) and minimum resistance to meropenem (25%) were observed. Out of 70 isolates, 25 (35.7%) were phenotypic beta-lactamase-producing enzymes. That highest percentage was related to wounds, equal to 12 (17%).
Conclusion: Considering the increasing prevalence of P. aeruginosa strains which produce extended-spectrum beta-lactamase, it is recommended to use an appropriate treatment protocol based on determining antibiogram pattern of strains. This means that all isolated before treating with antibiotics were examined by antibiotic susceptibility test. Also antibiotics should be used according to CLSI (Clinical and Laboratory Standards Institute). This issue is of serious concern for applying infection-control criteria with the purpose of preventing spread of this microbe.
Keywords: Disk diffusion antimicrobial tests, Pseudomonas aeruginosa, multi drug resistant, extended-spectrum beta-lactamase