A team led by researchers at the University of Maryland School of Public Health has found that the “superbug” methicillin-resistant Staphylococcus aureus (MRSA) is prevalent at several U.S. wastewater treatment plants (WWTPs).
Scanning electron micrograph of methicillin-resistant Staphylococcus aureus (MRSA)
Photo Credit: NIAID
MRSA is well known for causing difficult-to-treat and potentially fatal bacterial infections in hospital patients, but since the late 1990s it has also been infecting otherwise healthy people in community settings.
“MRSA infections acquired outside of hospital settings--known as community-acquired MRSA or CA-MRSA--are on the rise and can be just as severe as hospital-acquired MRSA. However, we still do not fully understand the potential environmental sources of MRSA or how people in the community come in contact with this microorganism,” says Amy R. Sapkota, assistant professor in the Maryland Institute for Applied Environmental Health and research study leader. “This was the first study to investigate U.S. wastewater as a potential environmental reservoir of MRSA.”
Because infected people can shed MRSA from their noses and skin and through their feces, wastewater treatment plants are a likely reservoir for the bacteria. Swedish researchers have previously identified the presence of MRSA in WWTPs in Sweden, and this new UMD-led study confirms the presence of MRSA in U.S. facilities. The study was published in the November issue of the journal Environmental Health Perspectives.
The research team, including University of Maryland School of Public Health and University of Nebraska Medical Center researchers, collected wastewater samples throughout the treatment process at two Mid-Atlantic and two Midwestern WWTPs. These plants were chosen, in part, because treated effluent discharged from these plants is reused as “reclaimed wastewater” in spray irrigation activities. The researchers were interested in whether MRSA remained in the effluent.
Reclaimed water or recycled water, is former sewage that is treated to remove solids and certain impurities, and used in landscaping irrigation. Researchers urge further study to evaluate the risk of exposure to antibiotic-resistant bacteria (MRSA) in treated wastewater.
They found that MRSA, as well as a related pathogen, methicillin-susceptible Staphylococcus aureus (MSSA),were present at all four WWTPs, with MRSA in half of all samples and MSSA in 55 percent.MRSA was present in 83 percent of the influent-- the raw sewage--at all plants, butthe percentage of MRSA- and MSSA-positive samples decreased as treatment progressed. Only one WWTP had the bacteria in the treated water leaving the plant, and this was at a plant that does not regularly use chlorination, a tertiary step in wastewater treatment.
Ninety-three percent of the MRSA strains that were isolated from the wastewater and 29 percent of MSSA strains were resistant to two or more classes of antibiotics, including several that the U.S. Food and Drug Administration has specifically approved for treating MRSA infections. At two WWTPs, MRSA strains showed resistance to more antibiotics and greater prevalence of a gene associated with virulence at subsequent treatment stages, until tertiary chlorination treatment appeared to eliminate all MRSA. This suggests that while WWTPs effectively reduce MRSA and MSSA from influent to effluent, they may select for increased antibiotic resistance and virulence, particularly at those facilities that do not employ tertiary treatment (via chlorination).
“Our findings raise potential public health concerns for wastewater treatment plant workers and individuals exposed to reclaimed wastewater,” says Rachel Rosenberg Goldstein, environmental health doctoral student in the School of Public Health and the study’s first author. “Because of increasing use of reclaimed wastewater, further research is needed to evaluate the risk of exposure to antibiotic-resistant bacteria in treated wastewater.”
The paper Methicillin-Resistant Staphylococcus aureus (MRSA) Detected at Four U.S. Wastewater Treatment Plants was written by Rachel E. Rosenberg Goldstein, Shirley A. Micallef, Shawn G. Gibbs, Johnnie A. Davis,Xin He, Ashish George, Lara M. Kleinfelter,Nicole A. Schreiber, Sampa Mukherjee, Amir Sapkota,Sam W. Joseph, and Amy R. Sapkota and published in the November 2012 issue of Environmental Health Perspectives.
For more information, please contact Kelly Blake, communications director for the School of Public Health at firstname.lastname@example.org or (301) 405-9418.
Kelly Blake | EurekAlert!
Further reports about: > Cancer treatment > Environmental Health > Environmental Health Perspectives > MRSA > MRSA infection > Maryland > Staphylococcus > Staphylococcus aureus > WWTPs > Wastewater > antibiotic-resistant bacteria > bacterial infection > environmental risk > health services > resistant bacteria > risk of exposure > superbugs > treated wastewater > wastewater treatment > wastewater treatment plant > water treatment > water treatment plants
Dune ecosystem modelling
23.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
Understanding animal social networks can aid wildlife conservation
23.06.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology