Targeting multidrug-resistant Escherichia coli by two isolated bacteriophages from hospital wastewater.

The growing emergence of antibiotic resistance has prompted the World Health Organization to include Escherichia coli on its list of global priority pathogens, highlighting the urgent need for new therapeutic strategies. This study was designed to isolate and characterize phage(s) against multidrug-resistant (MDR) E. coli and to evaluate their potential for inhibiting biofilms. Phages were isolated from hospital sewage and screened against 18 prophage-free clinical MDR E. coli isolates. Two phages, R8 and R9, were selected for further characterization. Their host range, efficiency of plating, one-step growth curve, and morphology were determined via transmission electron microscopy. The biofilm inhibitory efficacy of each phage, both individually and as a two-phage cocktail, was quantified using a microtiter plate assay. Two isolated bacteriophages, R8 and R9, belonging to the class Caudoviricetes, were identified. Both phages demonstrated a lytic spectrum against 38.8% of the tested MDR isolates. They exhibited short latent periods (20-22 min), with R9 displaying a significantly larger burst size (300 PFU/cell) than R8 (130 PFU/cell). Notably, phage R9, when applied alone, showed significantly superior biofilm inhibition compared to both phage R8 and the phage cocktail across various MOIs. The relatively broad host range, short latent phase, suitable burst size, and biofilm inhibitory effect demonstrate the potential of both phages-especially R9-for further analysis and consideration as candidates for therapeutic applications.