The use of antibiotics in people with COVID-19 could lead to raised levels of the drugs within rivers or coastal waters which may in turn result in an increase in antimicrobial resistance, according to a UK study.

Patients hospitalised due to the novel coronavirus infection are being given a combination of medications to prevent possible secondary bacterial infections, noted the researchers at the University of Plymouth in the UK.

The study, published in the Journal of Antimicrobial Chemotherapy, suggests their increased use during the pandemic could be placing an additional burden on waste water treatment works.

Scientists noted that this could lead to raised levels of antibiotics within rivers or coastal waters which may in turn result in an increase in antimicrobial resistance (AMR), where bacteria become resistant to the action of antibiotics.

This would be particularly acute in receiving waters from waste water treatment works serving large hospitals, or emergency hospitals, where there is a concentration of COVID-19 patients, they said.

The findings are based on reports that up to 95 per cent of COVID-19 inpatients are being prescribed antibiotics as part of their treatment, and concerns that such a large-scale drug administration could have wider environmental implications, according to the researchers.

"COVID-19 has had an impact on almost every aspect of our lives. But this study shows its legacy could be felt long after the current pandemic has been brought under control, said Sean Comber, Professor of Environmental Chemistry in Plymouth.

"From our previous research, we know that significant quantities of commonly prescribed drugs do pass through treatment works and into our water courses.

"By developing a greater understanding of their effects, we can potentially inform future decisions on prescribing during pandemics, but also on the location of emergency hospitals and wider drug and waste management," said Comber.

The COVID-19 guidance issued by the National Institute for Health and Care Excellence (NICE) suggests patients with COVID-19 should be treated with doxycycline and either amoxicillin or a combination of other medications if a bacterial infection is suspected, but to withhold or stop antibiotics if a bacterial infection is unlikely, the researchers said.

"Common with other hospitalised patients in the UK, and other countries, the majority of our patients with COVID symptoms were prescribed antibiotics because it is very difficult to know whether a patient presenting with symptoms of COVID has an overlying bacterial infection or not," Neil Powell, Consultant Pharmacist at the Royal Cornwall Hospital said.

"We did a lot of work to try and identify those patients who were unlikely to have a bacterial infection complicating their viral COVID infections in an attempt to reduce the amount of antibiotic exposure to our patients and consequently the environment," said Powell.

This research combined patient numbers for UK emergency hospitals set up temporarily around the country with waste water treatment work capacity and available river water dilution serving the emergency hospital and associated town.