PHENOTYPIC AND GENOTYPIC DETECTION OF EXTENDED-SPECTRUM Β-LACTAMASE (ESBL)-PRODUCING ESCHERICHIA COLI IN PATIENTS WITH COMMUNITY-ACQUIRED URINARY TRACT INFECTIONS

Background and Aim:Extended-Spectrum β-lactamases (ESBLs) are enzymes which cause resistance to most cephalosporins, penicillins and monobactams. There were various groups of ESBLs, including CTX-M, SHV and TEM enzyme types. β-lactam antibiotics are widely used for treatment of urinary tract infections (UTIs). The presences of ESBL-producing E. coli in UTIs can lead to treatment failure with the listed classes of antibiotics. Therefore phenotypic or genotypic detection of these isolates is important.Methods:Seventy eight E. coli isolates were obtained from 78 urine samples of patients with community-acquired UTIs. The isolates were studied for ESBLs production by combination disk diffusion method using cefotaxime (30μg), ceftazidime (30μg), ceftriaxone (30μg) and cefotaxime-clavulanic acid (30/10μg) disks. Presence of blaTEM, blaSHV, blaCTX_M genes were determined by PCR.Results:Prevalence of resistance to ceftazidime, ceftriaxone and cefotaxime were 42.3%, 53.8% and 55.12%, respectively. Since the ≥5 mm increase in the zone of inhibition diameter for cefotaxime-clavulanic acid compared to zone for cefotaxime alone indicates ESBL activity, the prevalence of ESBL-producing E. coli was 41%. Among the 32 ESBLs- producing E. coli, 29(90.6%) harbored CTX-M, 19(59.3%) harbored SHV, 4(12.5%) harbored TEM, 1(3.1%) harbored both TEM and CTX-M, 17(53.1%) harbored both SHV and CTX-M, and 2(6.25%) harbored all the three types of ESBLs.Conclusion:The worldwide increase in prevalence and spread of ESBL- producing E. coli can limit therapeutic options for UTIs and addition of healthcare costs. Therefore, the proper usage of extended-spectrum cephalosporins, regular surveillance of antibiotic resistance of clinical isolates and detection of ESBL-producers by accurate laboratory testing methods are crucial.

کلیدواژه ها:

E. coli ، Community-acquired UTIs ، ESBLs ، PCR