Study of antagonistic effects of Lactobacillus strains as probiotics on multi drug resistant (MDR) bacteria isolated from urinary tract infections (UTIs)

Abstract

<em>Objective(s):</em>Urinary tract infection (UTI) caused by bacteria is one of the most frequent infections in human population. Inappropriate use of antibiotics, often leads to appearance of drug resistance in bacteria. However, use of probiotic bacteria has been suggested as a partial replacement. This study was aimed to assess the antagonistic effects of <em>Lactobacillus </em>standard strains against bacteria isolated from UTI infections. <em>Materials and Methods:</em> Among 600 samples; those with ≥10,000 cfu/ml were selected as UTI positive samples. <em>Enterococcus </em>sp., <em>Klebsiella pneumoniae</em>, <em>Enterobacter </em>sp., and <em>Escherichia coli</em> were found the most prevalent UTI causative agents. All isolates were screened for multi drug resistance and subjected to the antimicrobial effects of three <em>Lactobacillus</em> strains by using microplate technique and the MICs amounts were determined. In order to verify the origin of antibiotic resistance of isolates, plasmid curing using ethidium bromide and acridine orange was carried out. <em>Results:</em> No antagonistic activity in <em>Lactobacilli</em> suspension was detected against test on <em>Enterococcus </em>and<em> Enterobacter </em>strains and<em> K. pneumoniae,</em> which were resistant to most antibiotics. However, an inhibitory effect was observed for <em>E. coli</em> which were resistant to 8-9 antibiotics. In addition, <em>L. casei</em> was determined to be the most effective probiotic. Results from replica plating suggested one of the plasmids could be related to the gene responsible for ampicillin resistance. <em>Conclusion:</em> Treatment of <em>E. coli</em> with probiotic suspension was not effective on inhibition of the plasmid carrying hypothetical ampicillin resistant gene. Moreover, the plasmid profiles obtained from probiotic-treated isolates were identical to untreated isolates.