Molecular Detection of Type II Toxin RelE Gene and Relation with Biofilm Formation in Escherichia Coli

Escherichia coli is the principal etiological agent of urinary tract infections (UTIs) and exhibits significant antibiotic resistance, driven by various virulence factors. Fifty E. coli isolates were obtained from 200 urine specimens of patients, and the relE gene was found to be crucial for antibiotic resistance and biofilm formation. This study used cultural and biochemical tests for primary bacterial isolate diagnosis, with the VITEK 2 System for confirmation. Antibiotic susceptibility testing assessed resistance, while the Congo red technique and microtiter plate method evaluated biofilm production. Multiplex PCR was used to detect the relE gene. Fifty isolates were tested by using the Congo red technique; 86% formed black colonies (biofilm producers), while 14% formed pink colonies (non-biofilm producers). The study found a 72% antibiotic resistance rate to cefotaxime among isolates. Minimum inhibitory concentration (MIC) values for cefotaxime only were 512, 64, and 32 µg/mL. Molecular detection of toxin-antitoxin type II genes via multiplex PCR on 22 isolates revealed that 12 (54.45%) possessed the relE gene. The gene expression was measured using quantitative reverse transcription PCR (qRT-PCR) in the presence and absence of sub-MIC concentrations of cefotaxime. The expression of the relE gene showed downregulation in all isolates, and fold changes were 0.1881, 0.2044, and 0.5864, respectively. The study concluded that changes in gene expression may be induced by environmental pressure or antibiotic resistance, suggesting disruption of the regulatory systems that maintain cell stability and persistence. This phenomenon is recognized as a bacterial defense mechanism.