In 2017, the World Health Organisation published the first list of antibiotic-resistant "priority pathogens" – bacteria that pose the greatest threat to human health. The top of the list - the most critical group - included pathogens in urgent need of new antibiotics. A research paper from Indian Institute of Technology, Delhi, has shown that the river Yamuna harboured some of these critical group, multidrug-resistant bacteria. They note that sewage was the main source of their entry into the river.
The team studied 20 major sewer drains and Yamuna river at five locations across New Delhi over two seasons and were able to isolate faecal coliform in abundance in all the samples. They also found bacteria that produce Extended-spectrum Beta-lactamases - enzymes that help bacteria resist many commonly-used antibiotics. Gene study showed the presence of resistance genes such as β-lactamases genes and carbapenemase in the studied samples. The team also noted the possibility of rapid proliferation of various antibiotic resistance genes among different bacteria through horizontal gene transfer.
“Poor sewage collection and lack of connectivity between drains and sewage treatment plants have worsened the situation,” noted the paper published in the Journal of Environmental Chemical Engineering .
“The need of the hour is adequate and appropriate infrastructure for sewage management. Many developing and developed countries have formed task forces to deal with the rising antibiotic-resistant pathogens in their rivers. We also need new interventions,” said Prof. Shaikh Ziauddin Ahammad from the Department of Biochemical Engineering and Biotechnology and the corresponding author of the work.
The team was able to map the pollutants and its possible source at the 20 different locations. A drain with a high abundance of resistant bacteria was possibly due to high anthropogenic activities and greater usage of advanced antibiotics in the posh areas. Previous studies have shown that antibiotic misuse, and self-medication is more in urban areas and people in posh areas have a high tendency to harbour resistant bacteria compared to the people living in rural or economically-deprived areas. Drains near hospitals and cattle farms also had a high abundance of antibiotic-resistant bacteria.
“These resistant bacteria can pose a serious threat to the health of the river water and there is also a high possibility of the spread of resistance to humans and animals. Our existing treatment plants work well with conventional organic pollutants like carbon, nitrogen, phosphorus; but with changing times and needs they need an upgrade,” added Manisha Lamba, first author of the paper who completed her Ph.D. from the institute.