Study of the Impact Antibiotic Combinations Used in Urinary Tract Infections on the Effectiveness of Antimicrobial Therapy
Jagoda Jeziurska-Pavlenko*, Dagmara Fydrych, Joanna Kwiecińska-Piróg, Jana Wełna and Emilia Siemińska
ABSTRACT
Biofilm-associated urinary tract infections (UTIs) represent a major therapeutic challenge due to their high tolerance to antimicrobial agents and frequent recurrence. The increasing prevalence of multidrug-resistant uropathogens necessitates the evaluation of alternative treatment strategies, including antibiotic combination therapy. The objective of this study was to assess the antibiofilm activity of selected antibiotics used individually and in combination against biofilms formed by clinically relevant uropathogens. The scope of the study included the evaluation of ciprofloxacin, nitrofurantoin, amikacin, and imipenem against biofilms of Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, and Enterococcus faecalis isolated from patients with urinary tract infections. Biofilms were formed on polystyrene microtiter plates and exposed to a range of antibiotic concentrations, applied both as monotherapy and in combinations. Biofilm biomass reduction was quantified spectrophotometrically using a crystal violet staining method. The reduction result was expressed as a percentage relative to the positive control, not exposed to antibiotics. The results demonstrated that antibiotic monotherapy produced only moderate reductions in biofilm biomass, with efficacy strongly dependent on bacterial species and antibiotic concentration. Ciprofloxacin and nitrofurantoin reduced biofilms of E. faecalis, P. aeruginosa, and E. coli by up to approximately 45%, while amikacin and imipenem showed variable activity against E. coli and P. mirabilis. In contrast, antibiotic combinations exhibited enhanced antibiofilm effects. The combination of ciprofloxacin with nitrofurantoin resulted in synergistic biofilm reduction, particularly against P. aeruginosa and E. coli. The most pronounced effect was observed for the imipenem–amikacin combination against P. mirabilis, achieving biofilm biomass reduction exceeding 80%. In conclusion, the findings indicate that antibiotic combination therapy is significantly more effective than monotherapy in reducing mature bacterial biofilms formed by uropathogens. These results support the potential clinical utility of rationally selected antibiotic combinations in the management of biofilm-associated urinary tract infections.
