Investigation the effect of nitric oxide on biofilm-producing uropathogenic Escherichia coli strains isolated from patients

Abstract

Background: Biofilm producing uropathogenic Escherichia coli (UPEC) strains are of major concern in clinical settings which display increased resistance to conventional antimicrobial therapy. Nitric oxide (NO) has shown to exhibit anti-biofilm effects in a variety of bacterial species. In this study we aimed to evaluate the effectiveness of NO on the formation and eradication of biofilm of UPEC strains isolated from patients with urinary infection (UI) in Tehran. Methods: During May 2022 to April 2023, a total of 3814 suspected isolates of UPEC were collected from a pathobiology laboratory in Tehran and confirmed as E. coli strains using specific primers for elongation factor Tu (tufA) gene. All strains were screened for the ability to form biofilm by the microtiter plate (MTP) and Congo red agar (CRA) assays, and also the presence of biofilm genes were detected among biofilm producing strains. Moreover, the effect of NO on biofilm formation and its dispersal was evaluated by the high (30 mM) and low (125 nM) concentrations of sodium nitroprusside (SNP) as NO donor. Results: All collected isolates were confirmed by the polymerase chain reaction (PCR) using specific primers, in which 1309 strains (34%) were able to form colonies with red, dry and rough (rdar, curli and cellulose positive) (n=682, 52%), brown, dry and rough (bdar, curli positive and cellulose negative) (n=353, 27%) and pink, dry and rough (pdar, cellulose positive and curli negative) (n=274, 21%) morphotypes on CRA and selected as biofilm positive strains. Furthermore, 228 (17%), 402 (31%) and 679 (52%) strains were able to form a weak, moderate, and strong biofilm, respectively, and csgA, csgD, yedQ, and bcsA genes were found among 87, 98, 100 and 79% of biofilm-positive strains, respectively. The 30 mM concentration of SNP significantly decreased the biofilm formation (17-40%) and increased biofilm dispersal (20-45%) among UPEC strains. Conclusion: These findings confirmed the applicability of nitric oxide as an anti-biofilm agent for UPEC strains. These findings contribute to the development of novel strategies for fighting biofilm-associated infections. Copyright © 2024 Rahimi et al.