HOST RANGE DIVERSITY AND ESCHERICHIA COLI GROWTH REDUCTION EFFICACY OF NOVEL BACTERIOPHAGES

Abstract

The emergence of multidrug-resistant (MDR) Escherichia coli has created an urgent need for alternative antimicrobial treatments. Bacteriophages are bacterial viruses with high host specificity and potent lytic activity, making them promising candidates for biocontrol and therapeutic applications. This study aimed to isolate, characterize, and evaluate lytic bacteriophages against MDR E. coli clinical isolates, with an emphasis on host-range determination and potential to reduce bacterial growth. Sewage samples were collected and processed for phage isolation using the agar overlay technique. Two lytic bacteriophages, designated EcoPhage-1 and EcoPhage-2, were isolated against MDR E. coli. Host range analysis was performed using spot assays against 10 E. coli isolates and several non-target bacterial species. Bacterial growth reduction assays were conducted at different multiplicities of infection (MOIs) over 24 h, with spectrophotometric analysis. EcoPhage-1 lysed 80% of the tested E. coli isolates, while EcoPhage-2 lysed 60%. Neither phage showed lytic activity against non-E. coli species, indicating high specificity. Both phages remained stable at pH 4–9 and temperatures up to 50 °C. Growth reduction assays demonstrated significant suppression of bacterial growth, particularly at MOIs of 1 and 10, with complete inhibition observed for up to 18 h. The results suggest that these bacteriophages possess strong antibacterial potential and may serve as alternative therapeutic agents against MDR E. coli infections.