Serotyping and virulence genes of Escherichia coli isolated from patients with recurrent urinary tract infection and uninfected control subjects: A case-control study

Abstract

Purpose

Escherichia coli (E. coli) isolates are the main cause of urinary tract infections (UTIs) worldwide. Several virulence factors, including biofilm and virulence genes, are recognized among E. coli isolates. We aimed to investigate serological typing and virulence factors among E. coli isolated from patients with recurrent UTIs compared to healthy controls.

Methods

This case-control study included 60 E. coli isolates. We collected urine and fecal samples from 20 patients with UTIs, as well as 20 fecal samples from healthy individuals. Antibiotic susceptibility testing was performed using the Kirby-Bauer disk diffusion method. We conducted O- and H- serotyping for all isolates using a slide agglutination method. Isolates were tested for biofilm formation and screened for six virulence genes (pap, sfa, afa, fimH, usp, and fyuA genes) using PCR. The significant p-value for comparisons between groups was set at ≤0.05.

Results

The overall O: H typeability was 53/60 (88.3 %). The most observed O:H serotyping pattern was O25:H2 (12/60, 20 %). The most frequent virulence genes among all E. coli isolates were fimH (53/60, 88.3 %) and fyuA (42/53, 70 %), followed by sfa (33/60, 55 %) and usp (24/60, 40 %). Pap was the least detected, found in only 10 isolates. The fimH gene was present in 100 % of fecal isolates from UTI patients compared to 70 % of fecal isolates from healthy controls (p = 0.02). Additionally, the usp gene was present in 45 % of fecal isolates from UTI patients and was only detected once among fecal isolates from healthy controls (p = 0.008). Twenty virulence gene patterns were detected.

Conclusion

Our findings confirm that most virulence genes were found in urine/fecal isolates from UTI patients, with a higher prevalence compared to fecal isolates from healthy controls.