Environmental surveillance of antimicrobial resistance in a rapidly developing catchment

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.