Distribution of Fimbrial Genes and Their Association with Virulence and Levofloxacin Resistance/Extended-Spectrum Beta-Lactamase Production in Uropathogenic Escherichia coli.

Background: Urinary tract infection (UTI) is predominantly caused by uropathogenic Escherichia coli (UPEC). Previous studies have reported that the fimbriae of UPEC are involved in virulence and antimicrobial resistance. We aimed to analyze the fimbrial gene profiles of UPEC and investigate the specificity of these expressions in symptomatic UTI, urinary device use, and levofloxacin (LVFX) resistance/extended-spectrum beta-lactamase (ESBL) production. Methods: A total of 120 UPEC strains were isolated by urine culture between 2019 and 2023 at our institution. They were subjected to an antimicrobial susceptibility test and polymerase chain reaction (PCR) to identify 14 fimbrial genes and their association with clinical outcomes or antimicrobial resistance. Results: The prevalence of the papG2 gene was significantly higher in the symptomatic UTI group by multivariate analyses (OR 5.850, 95% CI 1.390-24.70, p = 0.016). The prevalence of the c2395 gene tended to be lower in the symptomatic UTI group with urinary devices (all p < 0.05). In LVFX-resistant UPEC strains from both the asymptomatic bacteriuria (ABU) and the symptomatic UTI group, the expression of the papEF, papG3, c2395, and yadN genes tended to be lower (all p < 0.05). Conclusion: The fimbrial genes of UPEC are associated with virulence and LVFX resistance, suggesting that even UPEC with fewer motility factors may be more likely to ascend the urinary tract in the presence of the urinary devices. These findings may enhance not only the understanding of the virulence of UPEC but also the management of UTI.