Frequency of and risk factors for beta-lactamase-producing Escherichia coli Isolates in hospitalized patients

Escherichia coli, a member of the Enterobacteriaceae family, is responsible for a considerable rate of inpatient and outpatient infections. Recently, the rate of antibiotic resistance in E. coli infections and the production of β-lactamase, such as extended-spectrum β-lactamase (ESBL) and metallo-β-lactamase (MBL), has increased dramatically worldwide. The aim of this study was to evaluate the rate of and risk factors for β-lactamase production and to identify antibiotic resistance patterns in the public hospitals of a medical university in Iran. This was a cross-sectional study of 250 positive E. coli cultures collected between 2016 and 2018. We recorded age, sex, sample type (urine, blood, pus, and ascites), ward of admission, history of antibiotic use, administration over the previous month, and history of hospitalization in the last 3 months. Antibiotic resistance was identified by means of disk diffusion and confirmed with an epsilometer test. ESBL and MBL production were also assessed. Among 250 E. coli cultures, 40 (16%) produced MBL, 98 (32.9%) produced ESBL, and 123 (49.2%) had a multidrug-resistant (MDR) phenotype. In multivariate analysis, the odds of detecting MBL-producing E.coli isolates were lower with blood samples (odds ratio [OR] 0.17; p = 0.024) and hospital stays of