The First Large-Scale Wastewater Surveillance of AMR to inform Hyperlocal Antibiotic prescribing: A Study from Bengaluru, India

Approximately 1.2 million people died in 2019 globally due to antimicrobial resistant infections making it one of the major public health issues of the 21st century. Community level antibiotic resistance data is needed for guiding antibiotic prescriptions at the local level, which national databases may be unable to provide. We hypothesized that wastewater could have potential to detect local AMR patterns cost-effectively on a real time and longitudinal basis.

Our objectives were to explore the potential of wastewater to detect local AMR patterns of specific Gram Negative bacteria against 4 key antimicrobial classes across Bengaluru city. Wastewater from 66 open storm drain sites within all eight administrative zones of Bengaluru city, in southern India, between March and April 2022 were plated on McConkey and Shigella-Salmonella agar plates. 2 colonies were randomly picked from each plate, identified using standard biochemical tests and then subcultured for antibiotic sensitivity profiles against 5 common antibiotics: ciprofloxacin (Fluoroquinolone), cefixime (3rd generation cephalosporin), piperacillin/tazobactam (TZP, beta lactam/beta lactamase inhibitor), ertapenem and meropenem (carbapenems) on Mueller-Hinton plates

Of the 160 isolates selected for deeper scrutiny, 82% (132) belonged to the Enterobacteriaceae family. Of these, 95% (126) were known to cause human infections. About 28% of the clinically relevant Enterobacteriaceae isolates were susceptible to all five antibiotics tested while 12% were resistant to all five antibiotics, and the remainder had a mixed resistance profile. Our results indicate: a) drug resistant bacteria are found in significant numbers in open drains b) there is geographical variation within a city in the patterns and burden of AMR c) Wastewater could be both a method for estimating community burden of AMR. This is the first city-wide wastewater based AMR profiling in India and indicates the potential of such surveillance to provide hyperlocal community level data to influence local antibiotic prescription practices by primary care physicians and on antibiotic purchase and allocation decisions by government drug purchase committees.