Last week I wrote about a new type of antibiotic which targets bacteria in biiofilms. Ron Huber (Friends of Penobscot Bay) left an interesting comment:
“Of concern to us as … conservationists is whether these broad spectrum peptide antibiotics are digested by standard sewage treatment plant technology or pass essentially unscathed through the patient and the wastewater treatment facility and into the receiving waters. We want and absolutely need vigorous marine biofilms, an at a variety of scales and species mixes, if we are to have mussels, lobsters, clams, oysters and other organisms at all… Sewage plants are adaptable; can something be added that would bind with the antibiotic or otherwise render it harmless before discharge We would really like to know!” (full comment)
There has been much discussion about the misuse of antibiotics in agriculture and the impact of such careless use on human health. There has been rather less public discuss on on the environmental impact of antibiotic resides in sewage effluent. So apart from the environment, do antibiotic residues which survive sewage pose a risk to human health?
Yes they do (Selective pressure of antibiotic pollution on bacteria of importance to public health. (2012) Environmental health perspectives, 120(8), 1100). Consequently, there is a fair amount of research being carried out in this area – it just doesn’t make it into the press. Standard sewage treatment processes reduce but don’t eliminate antibiotics in sewage and these can contribute to the evolution and persistence of resistant pathogens in the environment (The effectiveness of sewage treatment processes to remove faecal pathogens and antibiotic residues. (2012) Journal of Environmental Science and Health, Part A, 47(2), 289-297). This paper shows that more advanced treatments such as membrane bioreactor technology reduce antibiotic resides more than the conventional activated sludge process, but still do not eliminate them completely from the wastewater.
What effect do these residues have on the environment? We really don’t know, but it seems likely that legislators are more likely to respond to the costs involved in improving sewage treatment via the human health argument rather than the environmental argument. Sad, but that’s how it is. As far as the new peptide antibiotic I wrote about last week is concerned, we simply don’t know yet how it will be affected by sewage treatment processes. But should we be worried about such criteria when introducing new compounds for therapeutic use? Yes we should. Of course, it’s not just antibiotics we have to worry about.