Phenotypic and molecular evaluation of biofilm-forming ability of bacterial strains isolated from patients with urolithiasis

This study aims to identify the common causative agents of urinary tract infections (UTIs) in patients with urolithiasis and to evaluate the phenotypic and molecular biofilm-forming ability of these agents. A total of 100 patients diagnosed with kidney stones who presented with UTI symptoms were included in this prospective cross-sectional study conducted from April till August 2022 at the Kerkuk Education and Research Hospital. Routine conventional methods were used to identify clinically significant bacteria from urine samples. Antibiotic susceptibility tests were performed using the disk diffusion method for the isolated bacteria. VITEK® 2 (bioMérieux, France) commercial identification and susceptibility systems were used when necessary. Biofilm formation of the detected agents was examined by the microplate method, and the molecular detection of some genes associated with biofilm was performed. Significant growth was observed in 60% of the urine samples obtained from the patients. The most frequently isolated agents were Escherichia coli (n: 36), Proteus mirabilis (n: 17), Staphylococcus aureus (n: 3), Klebsiella pneumoniae (n: 2), and Pseudomonas aeruginosa (n: 2), respectively. Imipenem was found to be the most sensitive antibiotic for E. coli and P. mirabilis strains. Biofilm formation was observed in 89% of the isolated E. coli strains and 94% of the P. mirabilis strains. The foc gene was detected in 24 of the 36 E. coli isolates, while the sfa gene was detected in 20 of them. Of the 17 P. mirabilis isolates, 12 had the pfmA gene, and 10 had the mrpA gene. The results obtained are particularly important in terms of the high biofilm formation and the frequent occurrence of genes associated with this biofilm formation in E. coli and P. mirabilis strains. We believe that our study may contribute to the development of effective strategies that can be used in the treatment and prevention of urinary tract infections in patients with urolithiasis.