Comparative evaluation of biofilm-forming capacity in uropathogenic and commensal Escherichia coli

Abstract

Introduction: Escherichia coli (E. coli) causes most cases of the urinary tract infections (UTIs) via virulence factors like biofilms. This study identifies key phenotypic and genotypic virulence attributes of Uropathogenic Escherichia coli.

Methodology: A total of 180 uropathogenic E. coli (UPEC) isolated from patients with different categories (cystitis, pyelonephritis, recurrent UTI, catheter-associated UTI, and asymptomatic bacteriuria) of UTI and 30 commensal E. coli isolated from healthy individuals were evaluated for biofilm production by phenotypic methods using tissue culture plate, tube adherence, and Congo red method, and RT-PCR was used to genetically characterize them.

Results: This study analyzed 1,600 urine samples from UTI patients, with 498 showing significant bacterial growth and 180 identifying E. coli as the pathogen. The female-to-male ratio of UTI cases was 0.74. Antibiotic susceptibility testing revealed 100% sensitivity to tigecycline and fosfomycin as well as 89.44%, 86.11%, 81.66%, and 72.22% sensitivity to nitrofurantoin, amikacin, imipenem, and meropenem, respectively. Only 64.44% were sensitive to ciprofloxacin, with 10% being multidrug-resistant (MDR). Moreover, 18.33% of the UPEC isolates produced mettalo-beta-lactamases (MBL), and 13.33% produced AmpC beta-lactamases. Biofilm production was observed in 72.22% of UPEC isolates compared to 16.66% in commensal isolates. The biofilm-forming UPEC, compared to commensal E. coli, has significantly higher antibiotic resistance, with a 128-fold reduction in ciprofloxacin susceptibility. Additionally, the fimH gene was detected in 98.33% of the UPEC isolates.

Conclusion: This study shows that UPEC strains produce specific virulence determinants like adhesion to uroepithelial cells. Screening for virulence factors should be integrated into microbiology laboratories. Specific virulence genes linked to UPEC may serve as potential targets for prophylactic strategies to prevent recurrent infections and improve management.

Keywords: Congo-red method; biofilm production; multiplex PCR; tissue culture plate method; urinary tract infection; uropathogenic Escherichia coli.