EPA-funded research- Antibiotics and antibiotic resistant bacteria in our sewers

Date released: Jan 14 2016

EPA-funded research - Antibiotics and antibiotic resistant bacteria in our sewers

The EPA has today published the results of research by scientists at the School of Medicine and Centre for Health from Environment at NUI Galway and colleagues at UCD.  This research looked at whether antibiotics and antibiotic resistant bacteria are present in hospital sewage, and city sewage.

Dr Brian Donlon, Head of Research, EPA Office of Evidence and Assessment commented;

“Water quality is threatened by new emerging contaminants, such as pharmaceuticals, personal care products  and emerging pathogens (including antibiotic resistant bacteria and viruses).  Wastewater is considered to be the main source of  entry of antimicrobials/antibiotics and antibiotic-resistant bacteria into the environment The researchers tested to see if the antibiotic resistant bacteria can survive wastewater treatment processes and examined what (if any) is the possible risk of antibiotic resistant bacteria, which is discharged into seawater from treatment plants, getting back into people.”

The research team found high levels of bacteria resistant to all antibiotics in urban sewage from hospitals and from the general city sewage. Hospital sewage was different in that there were high levels of bacteria resistant to a number of “newer” antibiotics.
The number of antibiotic resistant bacteria present were reduced greatly by effective wastewater treatment, but some antibiotic resistant bacteria survive and are discharged to seawater.

The team consider that the risk of people coming in contact with antibiotic resistant bacteria from swimming in seawater receiving properly treated sewage is very low.

The team also found that the predicted discharges of antibiotics into the environment from hospitals is substantial. There is evidence that some antibiotics may persist in the water and soil for long periods.

Dr Dearbháile Morris, NUIG said:


“This study highlights a part of the problem of antibiotic resistance that does not receive very much attention. Our work shows that there is a risk related to antibiotics and antibiotic resistant bacteria in sewage but that a high standard of sewage treatment goes a long way to reduce that risk. This is one more reason why the discharge of untreated or inadequately treated sewage to the environment in Ireland or indeed anywhere in Europe or the wider world is an unacceptable risk to our health.”

The report, entitled Hospital effluent: impact on the microbial environment and risk to human health is now available on the EPA website.


Notes to Editors:

Antibiotic resistance is one of the greatest threats to public health.  Bacteria are becoming resistant to more and more antibiotics and infections are more and more difficult to treat. Hospitals today are fighting the problem of infections caused by bacteria resistant to so many antibiotics that patients with these infections are very difficult to treat. Antibiotic resistance is driven by contact between bacteria and antibiotics. When we take antibiotics to treat an infection the antibiotic impacts on all the bacteria in the body not just the one causing the infection. This can drive many bacteria in the gut and skin towards antibiotic resistance. In the past we have paid much less attention to contact between antibiotics and bacteria outside the body. However a lot of the antibiotics we swallow come out in urine or faeces. Bacteria are also shed in faeces and become mixed with water and soil bacteria in sewers and treatment plants. In recent years there has been growing interest in the way in which this melting pot of bacteria and antibiotics might also contribute to this major problem of antibiotic resistance.  Hospitals use a lot of antibiotics. About 1 in 3 patients in hospital are on antibiotics at any one time. Hospitals tend to use high doses or the newest and most broadly acting antibiotics because of the nature of the infections in hospitalised patients.