---

Background and Objectives: Recently, the use of probiotics for the treatment of Urinary Tract Infections has become more popular. The use of probiotics in therapy is useful as only a few side effects such as destruction of resistant bacteria or disturbance of the intestinal microbiota have been reported. The aim of this study was to evaluate the probiotic effects of lactic acid bacteria by co-aggregation of ciprofloxacin-resistant uropathogenic Escherichia coli strains using microbial techniques.
Materials and Methods: Three strains of Lactobacillus plantarum, Lactobacillus casei and Lactobacillus acidophilus were provided. Twenty isolates of uropathogenic Escherichia coli were collected from Shahid Labbafinejad hospital, Tehran. Eight samples with resistance to ciprofloxacin were selected using the disk diffusion method for the co-aggregation test. PCR was used to evaluate the presence of qnrA and qnrS genes in ciprofloxacin-resistant isolates. To evaluate the antimicrobial activity of complete culture and supernatants of lactobacilli, modified double-layer culture method and well diffusion methods were used, respectively. Co-aggregation of lactobacilli was evaluated by the co-aggregation test and microscopy test.
Results: Results showed that the eight human isolates were resistant to ciprofloxacin among other samples. Only one strain had both qnrA and qnrS genes simultaneously. L. plantarum with the average growth inhibition zone of 42 mm and with 65% of the co-aggregation had the best probiotic effects among all lactobacilli bacteria.
Conclusions: The probiotic lactobacilli had spectacular antimicrobial effects against the ciprofloxacin-resistant uropathogenic Escherichia coli strains. Also, lactobacillus spp. were aggregated with uropathogenic Escherichia coli strains and preventing from their adhesion to specific receptors on the Urethra, thus, the subsequent invasion to the host was prevented.