Seasonal Dynamics of Multidrug-Resistant Escherichia coli and Potential for Bacteriophage Based Biocontrol from Wastewater in Mumbai, India

Abstract

Aims: The global emergence of multidrug-resistant (MDR) pathogens poses a severe threat to public health, with wastewater treatment plants (WWTPs) emerging as critical reservoirs for the dissemination of antibiotic resistance. This study investigated the seasonal prevalence of MDR Escherichia coli strains in six different WWTPs across Mumbai and isolated bacteriophages against them, exploring the potential of bacteriophages as a sustainable biocontrol strategy. Study Design: A cross-sectional study was conducted over 12 months to analyze seasonal trends of MDR E. coli and isolate corresponding bacteriophages from wastewater. Place and Duration of Study: Samples were collected from six WWTPs across Mumbai, India, over a 12-month period. Methodology: A total of 106 E. coli strains were isolated from wastewater samples. Among them, 86 (81.1%) were identified as multidrug-resistant based on resistance to more than three antibiotics. Seasonal distribution and resistance profiles were analyzed statistically. Bacteriophages were isolated and characterized for plaque morphology and host range using the enrichment and double-layer agar methods. Results: The occurrence of MDR E. coli showed a distinct seasonal trend, peaking during winter (48%), followed by summer (28%) and monsoon (24%), indicating the influence of climatic and environmental factors. Statistical analysis confirmed that the variation in seasonal prevalence was significant (χ²= 8.11, df = 2, p < 0.05). Resistance profiles varied across seasons and antibiotic classes, with β-lactam resistance notably reduced during the monsoon, possibly due to environmental dilution or degradation. Penicillin G and erythromycin maintained high resistance across all seasons. Bacteriophages were successfully isolated against 55 of the 86 MDR E. coli strains. Characterization of the phage isolates revealed varied but often multi-strain host ranges, and lytic activity was confirmed through clear plaque formation. Conclusion: This study provides critical insights into the seasonal dynamics of MDR E. coli in urban wastewater and establishes the potential of bacteriophages as effective tools for controlling antibiotic-resistant bacteria. Integrating environmental surveillance with phage-based interventions may contribute significantly to mitigating the global antibiotic resistance crisis.