Evaluation of Biofilm Formation and Antibiotic Resistance Pattern in Extended-Spectrum β-Lactamase-Producing Escherichia coli Strains

Background: The increasing prevalence of multidrug-resistant (MDR) Escherichia coli strains, especially extended-spectrum beta-lactamase (ESBL)-producing strains, has become a global health concern. This study was aimed to determine the frequency of bla(CTX-M), bla(TEM), and bla(SHV) genes among E. coli isolates from urinary tract infection (UTI) and evaluate their antibiotic resistance pattern. Methods: Totally 98 E. coli isolates were recovered from urine samples of UTI-diagnosed patients. Antibiotic resistance and ESBL production were evaluated by disk diffusion and combined disk methods according to the Clinical Laboratory Standards Institute guidelines. The biofilm formation ability of isolates was assessed using the tube adherence method. ESBL-positive isolates were screened for bla(TEM), bla(CTX-M), and bla(SHV) genes by polymerase chain reaction. Results: Among the examined isolates, 25 (25.5%) were detected as ESBL producers and harbored at least one of the studied genes. The bla(CTX-M) was the predominant (44%) gene, followed by bla(TEM) (24%) and bla(SHV) (8%). The isolates revealed variable resistance levels to all antimicrobials, out of which 55.1% were conferred a high resistance rate to different antibiotic classes and considered MDR. Phenotypically, 42.85% of the isolates were biofilm formers, of which the majority (38%) formed moderate biofilms. Conclusions: This study showed that the ESBL-positive isolates were more resistant to some first-line antibiotics, and this highlights the necessity to control and monitor the prescribed antibiotics used for empirical treatment for UTI patients.