Antibiotic Resistance and Virulence Gene Profiling of Uropathogenic Escherichia coli Isolated from Clinical Samples

Background: Urinary tract infection (UTI) is the third most prevalent type of infection, following respiratory and gastrointestinal infections. Uropathogenic E. coli (UPEC) is a subset of extraintestinal pathogenic E. coli with a wide range of genotypes responsible for causing UTIs. This study aimed to detect the antibiotic resistance and virulence genes of local isolates of UPEC from UTIs and to determine biofilm formation by UPEC isolates. Methods and Results: One hundred urine samples were obtained from patients with UTIs from hospitals in Baghdad from September 2023 to December 2023 and then plated for 24 hours at 37°C on McConkey agar. Biochemical tests and the VITEK-2 system were used to identify UPEC isolates. The antibiotic susceptibility test was performed using the disc diffusion technique, and the results were identified according to the guidelines of CLSI 2023. The biofilm formation was determined by an ELISA reader at OD570 using the microtitre-plate technique. Detection of csgA and fimH genes was performed by PCR. Fifty-two (52%) isolates of UPEC were identified from 100 urine samples. The results revealed that 100% of the isolates were resistant to ceftazidime, 92.3% to gentamicin, 90.4% to ciprofloxacin, 84.6% to azithromycin and aztreonam, and 46.1% to imipenem. Out of 52 isolates, 39(75%) have multiple resistance to more than three antibiotics. The results demonstrated that 12% of the isolates were strong biofilm producers, 40% - moderate biofilm producers, 36% produced weak biofilms, and 12% did not produce biofilms. The csgA and fimH genes were detected in 47(90%) and 49(94%) isolates, respectively. Conclusion: This study demonstrated that elevated resistance rates were noted against administered antibiotics, signifying an increasing problem in effectively treating UTIs; 75% of the isolates showed an MDR phenotype. The study also verified the capacity of UPEC to produce biofilms (88% of isolates) and express virulence factors, enhancing their pathogenicity and treatment resistance.