Isolation and phenotypic characterization of bacteriophages targeting multidrug-resistant biofilm-forming uropathogenic Escherichia coli from hospital sewage

Abstract Uropathogenic Escherichia coli (UPEC) is a major cause of urinary tract infections (UTIs), with multidrug resistance (MDR) and biofilm formation complicating treatment. This study isolated and phenotypically characterized bacteriophages targeting MDR and biofilm-forming UPEC from hospital sewage in Ethiopia. Twenty-three archived MDR UPEC isolates were screened for biofilm formation, and phages were characterized by host range, efficiency of plating, multiplicity of infection (MOI), adsorption kinetics, one-step growth, environmental stability, and biofilm biomass reduction. Eight isolates (34.8%) formed biofilms, including 3 strong, 1 moderate, and 4 weak biofilm formers. Two phages, ΦET-3175 and ΦFETA-207, were isolated with titers of 1.35 × 10⁹ and 1.12 × 10⁹ PFU/mL, respectively. ΦET-3175 showed broader activity, with detectable activity against 6/23 (26.1%) isolates, an optimal MOI of 0.1, > 95% adsorption within 20 min, a latent period of approximately 30 min, and a burst size of 147 ± 4.6 PFU per infected cell. Both phages retained detectable activity across pH 4–10 and at temperatures up to 50 °C. ΦET-3175 reduced biofilm biomass by 3.2–39.5% among four susceptible biofilm-forming isolates, but the paired difference was not statistically significant (Z = − 1.826, p = 0.068). These findings provide preliminary in-vitro phenotypic evidence and support further genomic, structural, and biological characterization.