Environmental carbapenem-resistant Acinetobacter baumannii in wastewater receiving urban river system of eastern India: a public health threat

The present study determined the effect of untreated wastewater on the prevalence of carbapenem resistance in Acinetobacter baumannii (CRAB) in both the wastewater and the receiving river water surrounding Cuttack City. Physiochemical parameters, heavy metal contamination factors (CF), contamination degree (CD), pollution load index (PLI), and microbiological content (total coliform, fecal form, and CRAB) were analyzed in two untreated urban wastewater and three in receiving river water (upstream, catchment, and downstream). The high BOD, CF, CD, and PLI in urban wastewater, river catchment, and downstream revealed intense anthropogenic activity. After bla(OXA-51) detection and clonal analysis by ERIC-PCR, a total of 73 CRAB were selected for further analysis. All the CRAB isolates were 100% resistant to penicillin, beta-lactam/beta-lactamase inhibitor, cephalosporin, and carbapenem groups of antibiotics. The antibiotic profile showed 73.97% CRAB isolates assigned as extremely drug resistant. Detection of carbapenemase (bla(NDM) and bla(OXA-48)) and co-harboring ESBL (bla(TEM)) genes, the highest at the river, reflects direct disposal of biomedical wastes. MAR index (> 0.2) and virulence index (> 0.5) in 59 isolates were classified as a high threat posing a severe human risk. A similar ERIC pattern between the isolates from two different locations (catchment and downstream) indicates their dissemination downstream through river water flow. The extraordinary ability of resistant A. baumannii to thrive in the river makes it unfit for household activities and poses a public health threat. Therefore, frequent monitoring of resistance levels in water could help direct antibiotic use and resistance management.

Automated summary

This study determined the impact of untreated wastewater on the prevalence of carbapenem resistance in Acinetobacter baumannii (CRAB) in the surroundings of Cuttack City. The results showed intense anthropogenic activity and high pollution load in both urban wastewater and receiving river water. The presence of carbapenem-resistant A. baumannii in the river indicates the risk of dissemination downstream.