Soil, water and vegetables contaminated with antibiotic-resistant bacteria
According to the European Commission, antimicrobial medicines and micro-organisms resistant to these medicines in the environment constitute one of the biggest health threats in the world (Vytenis Andriukaitis, EU Commissioner for Health and Food Safety, March 2019).
Recent research by the RIVM shows that manure from pigs, cows, chickens, etc. as well as water that flows from sewage treatment plants contain many bacteria that are insensitive to certain types of antibiotics.
Manure and waste water from wastewater treatment plants polluted
RIVM investigated how many ESBL-producing E. coli bacteria end up in the soil and water via manure. The highest concentrations of ESBL-producing E. coli were found in manure from laying hens. These and other animals are regularly given antibiotics. This makes the intestinal bacteria of the animals resistant to several types of antibiotics. These multi-resistant bacteria then end up in the manure.
In addition to manure from farm animals, water (“effluent”) from sewage treatment plants is also an important source of resistant bacteria in the environment. Resistant bacteria in sewage come from human stools. Because the bacteria in the sewage treatment plant are not completely removed, they end up in the rivers, streams and canals that these plants discharge into. According to RIVM, people in contact with surface water contaminated with effluent and agricultural ditch water can come into contact with these multi-resistant bacteria of human and veterinary origin.
The RIVM study also shows that the total amount of multi-resistant bacteria that end up on the soil via manure is approximately the same as the amount that ends up in surface water via the effluent. Nevertheless, from manure and soil, only some of the resistant bacteria end up in surface water. Therefore, according to the researchers, effluent is a larger source of resistant bacteria in surface water than manure.
Contamination of agricultural crops
However, agricultural crops can also be contaminated. It is known that raw meat is an important source of multi-resistant bacteria. That raw vegetables can also be a source is less known. For example, a German study from 2018 showed that lettuce can be a reservoir of antibiotic resistance (Blau K et al. 2018). Research in the US (2019) shows that resistant bacteria from vegetables can colonize the intestines.