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Updated: Aug 24, 2025
Author Spotlight: Understanding and Detecting Environmental Antimicrobial Resistance by Combining Culture-Based Techniques and Genomics
Published on: July 19, 2024
Environmental surveillance of antimicrobial resistance in a rapidly developing catchment
Akash Ashwini1, Priyanka Jamwal2, Abi Tamim Vanak1,3,4
1Ashoka Trust for Research in Ecology and Environment, Jakkur post, Bengaluru, India.
Abstract:
Development and spread of AMR from various sources such as hospitals, pharmaceutical industries, animal farms and human habitations is not well understood. We conducted a pilot study to assess the prevalence of AMR by taking a case of rapidly developing catchment in Western India. For this, we selected four sub-catchments/regions with a dominant source of antibiotics, viz. areas with (a) dense poultry farms (4 farms/km2), (b) sparse number of poultry farms (2 farms/km2), (c) agricultural fields and (d) habitation (village). The environmental samples (soil, litter and water) were subjected to Kirby-Bauer/antibiotic disc susceptibility test to assess the resistance pattern in the bacterial species. Preliminary investigations showed the presence of seven multidrug-resistant bacterial species in the litter from poultry farms, with five species having a MAR index greater than 0.2. No evidence of AMR was observed in the vicinity (water and soil) of the poultry farms. This could be attributed to the rigorous disinfection protocols followed at the poultry farms to prevent infection in the fresh batch of chickens. However, in agricultural fields where the litter is used as manure, seven multiple drugs resistant with two species scoring a MAR index greater than 0.2 were observed. MAR index of less than 0.2 was observed for Escherichia coli and Enterobacter species isolated from village and control site (soil), respectively, indicating negligible contamination by antibiotics at sub-catchments. This study provides an approach to investigate the effects of multiple factors on the prevalence of AMR at the catchment scale.
Insights
Antibiotic resistance (AMR) spread from poultry farms is concerning. While poultry litter showed multidrug-resistant bacteria, nearby soil and water were clear, but agricultural fields using litter as manure showed significant AMR.
Area of Science:
- Environmental microbiology
- Antimicrobial resistance (AMR)
- One Health
Background:
- The development and spread of antimicrobial resistance (AMR) from diverse sources, including animal farms, remain poorly understood.
- Assessing AMR prevalence requires investigating various environmental compartments and their connectivity.
- Poultry farming is a significant contributor to antibiotic use and potential AMR dissemination.
Purpose of the Study:
- To pilot an investigation into the prevalence and patterns of AMR in a developing catchment area.
- To assess AMR in environmental samples (soil, litter, water) from regions with varying proximity to poultry farms, agricultural fields, and human habitations.
- To evaluate the impact of poultry litter as manure on AMR in agricultural soils.
Main Methods:
- Selection of four sub-catchments with distinct antibiotic source dominances: dense poultry farms, sparse poultry farms, agricultural fields, and a village.
- Collection of environmental samples: soil, litter, and water.
- Application of Kirby-Bauer antibiotic disc susceptibility testing to identify resistant bacterial species and calculate the Multiple Antibiotic Resistance (MAR) index.
Main Results:
- Seven multidrug-resistant bacterial species were identified in poultry farm litter, with five exhibiting a MAR index > 0.2.
- No AMR evidence was found in soil and water samples immediately surrounding poultry farms, likely due to disinfection protocols.
- Agricultural fields utilizing poultry litter as manure showed seven multidrug-resistant species, with two having a MAR index > 0.2; village and control soil samples indicated negligible contamination.
Conclusions:
- Poultry farm litter is a reservoir for multidrug-resistant bacteria.
- The use of contaminated litter as manure in agricultural fields significantly contributes to the spread of AMR.
- The study demonstrates a scalable approach for catchment-level AMR surveillance, highlighting the importance of manure management.
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