Environmental Dissemination of Multidrug-resistant Bacteria through Hospital Wastewater: Impact of Treatment...

Antimicrobial resistance (AMR) is a global public health challenge, with hospital wastewater serving as an important reservoir and dissemination pathway for resistant pathogens. Wastewater Treatment Plants (WWTPs) are critical in reducing microbial load and limiting the environmental release of multidrug-resistant (MDR) organisms.

This study aimed to isolate and characterize antibiotic-resistant bacteria from hospital wastewater before and after treatment, and to assess the effectiveness of the effluent treatment plant (ETP) in reducing resistant organisms.

An analytic observational study was conducted at the ETP of Maharishi Markandeshwar Medical College and Hospital, Himachal Pradesh, between August 2022 and October 2022. Pretreatment and posttreatment wastewater samples were collected on alternate days and processed using standard microbiological methods. Bacterial isolates were identified, and their antimicrobial susceptibility patterns were determined. Data were analyzed using IBM SPSS Statistics v28.

Pretreatment samples predominantly contained Staphylococcus aureus (24.42%), Escherichia coli (18.42%), Enterococcus faecalis (17%), Pseudomonas aeruginosa (16.82%), Klebsiella pneumoniae (8.57%), Proteus mirabilis (11.42%), and Bacillus subtilis (3.35%). Posttreatment samples showed a marked reduction in bacterial load, with elimination of B. subtilis and P. mirabilis. Antimicrobial susceptibility testing revealed significant improvement in sensitivity among surviving isolates, particularly E. coli (88% sensitivity) and K. pneumoniae (82% sensitivity).

Hospital wastewater is a potential reservoir of MDR pathogens that may persist beyond treatment and contribute to environmental dissemination. Effluent treatment significantly reduced bacterial burden and resistance rates, highlighting the importance of WWTPs in mitigating AMR. Strengthening treatment technologies and implementing strict monitoring are essential to prevent community exposure to resistant pathogens.