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

Abstract

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 < 7 days (OR 0.02; p < 0.001), whereas the odds of detecting ESBL-producing E. coli isolates were lower with no recent hospital stay (OR 0.28; p = 0.001) and < 7 days of hospitalization (OR 0.34; p = 0.009). However, the analysis showed a statistical increase in the risk of detecting ESBL in patients who had recently used antibiotics (OR 2.50; p = 0.01). The lowest rate of resistance was to meropenem (0.4%) or imipenem (2.4%) for all strains in terms of MBL, ESBL, and MDR seroprevalence. The highest rate of resistance was to ceftazidime (62.4%). A high rate of MBL- and ESBL-producing E. coli in this study, and the presence of antibiotic resistance to carbapenems, may be an alarming sign of an increased rate of MDR in the near future. These results can be traced back to a variety of inappropriate and unnecessary antibiotic prescriptions for outpatients and inpatients. Further related studies are strongly recommended.