Evaluation of Bacteriophage Activity Against Escherichia Coli and Klebsiella Pneumoniae Isolates from Hospital Sewage Water at a Tertiary Care Hospital

Abstract

Background: Antimicrobial resistance (AMR) in Escherichia coli and Klebsiella pneumoniae has become a critical global health challenge, limiting therapeutic options. Bacteriophages, owing to their host‑specific antibacterial activity, represent a promising alternative. This study assessed the lytic potential of sewage‑derived phages using spot and double‑layer agar (DLA) assays.

Objective: To evaluate the lytic activity of bacteriophages isolated from hospital sewage against multidrug‑resistant (MDR) E. coli and K. pneumoniae.

Methods: Six MDR isolates (three E. coli, three K. pneumoniae) were tested. Phages were isolated via enrichment and DLA plaque assays. Antimicrobial susceptibility was determined per CLSI guidelines. Lytic activity was assessed using spot assay, DLA plaque counts, and efficiency of plating (EOP).

Results: Two isolates exhibited strong lysis with confluent plaques, two showed moderate lysis, one weak lysis, and one was resistant. Overall, 66.7% of isolates were susceptible. The EOP for E. coli was 0.58 (moderate infectivity), while K. pneumoniae showed confluent lysis without countable plaques. Statistical analysis confirmed significance (t = 3.62, df = 5, p < 0.05).

Conclusion: Sewage‑derived bacteriophages demonstrated significant lytic activity against MDR pathogens, supporting their potential as alternative therapeutic agents.