Study of Inhibitory Estimates of Probiotics and Extent of their Synergistic Effect with some Antibiotics Against Antibiotic-Resistant Bacteria that Cause Urinary Tract Infections in Children

Abstract

The prevalence of urinary tract infections (UTIs) in children caused by antibiotic-resistant bacterial strains represents a serious public health problem. The aim of this in vitro study was to evaluate the direct antimicrobial activity of commercially available probiotic strains and to investigate their synergistic interaction with antibiotics against clinical isolates of uropathogens. From 160 urine samples, 65 antibiotic-resistant bacterial isolates (both Gram-positive and Gram-negative) were obtained. Their identification and resistance profiling were performed using the VITEK-2 system. The antimicrobial activity of probiotics and their synergism with antibiotics were assessed using the agar diffusion method. The results showed that certain probiotic strains, particularly L. rhamnosus and L. reuteri, exhibited significant inhibitory activity against uropathogens, whereas others (Bifidobacterium) were inactive. The strongest synergistic effect was observed with the combination of probiotics and tetracycline. The findings demonstrate that the antimicrobial effects and synergism with antibiotics are strictly strain-dependent and vary with the antibiotic’s mechanism of action. This in vitro study highlights the potential utility of probiotics as adjunctive agents to overcome antibiotic resistance and emphasizes the need for further investigation of strain-specific interactions.