Evaluation of Antimicrobial Susceptibility in Extended-Spectrum β-Lactamase Producing Escherichia coli Isolates From Patients in Northwest Iran

Background: Escherichia coli is one of the main causes of various diseases worldwide, whose multidrug-resistant strains have caused many public health problems by producing extended-spectrum β-lactamases (ESBLs). The resistance rate varies in different regions. Thus, it is necessary to identify ESBL-producing strains in each region and their antibiotic sensitivity in order to find appropriate treatment options. Hence, the present study aimed to detect the ESBL-producing E. coli strains and their antimicrobial susceptibility pattern in Tabriz, Iran. Methods: This study was conducted at the Imam Reza Hospital in Tabriz from November 20, 2022, to April 20, 2023. A total of 400 E. coli isolates were collected from different clinical specimens. Antimicrobial susceptibility testing was performed by the disk diffusion method. ESBL-producing isolates were detected by the double-disc synergy test method according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. Results: Out of 400 E. coli isolates, 211 (52.75%) were obtained from females, and 189 (47.25%) belonged to males. The mean age of patients was 52.1±27.9 years. Overall, 279 (69.75%) were confirmed as ESBL producers. These producers were mainly recovered from outpatients. The highest antibiotic resistance was observed to ceftriaxone (86.25%) and tetracycline (80.75%), and the least antibiotic resistance was related to imipenem (8%) and amikacin (16.25%), respectively. The rate of antibiotic resistance among ESBL producers was higher than among non-ESBLs. Conclusion: The present study reported a high prevalence of ESBL-producing E. coli among patients referring to Imam Reza hospital in Tabriz. Carbapenems, aminoglycosides, and nitrofurantoins were confirmed as the most efficient drugs for these bacteria, whereas cephalosporins, fluoroquinolones, and sulfonamides were the least effective agents.