According to a study in the Journal of Health and Pollution, researchers at The University of Texas at El Paso (UTEP) and El Paso Community College (EPCC) discovered that the Rio Grande is a “hotspot” for multidrug-resistant bacteria, antibiotic residues and antimicrobial resistant genes, which “may represent a public health concern” for people who use the river on both sides of the U.S. and Mexican border.
“We know there is bacteria in the Rio Grande’s water, but we wanted to see if there was antibiotic multidrug-resistant bacteria and residues because the water from the river is treated as potable drinking water and kids and their families go and swim there, especially from Mexico,” said Maria Fuentes, a student in UTEP’s Interdisciplinary Health Sciences Ph.D. Program and the paper’s first author.
“This could potentially be a public health issue because if you come into contact with the contaminated water, it could lead to more gastrointestinal infections,” she added. “It could also contribute to the problem of antibiotic resistance through the development and spreading of more genes of resistance in the environment. However, more research needs to be done to see how serious of a public health concern this is.”
Fuentes participated in the yearlong 2017 study led by Delfina C. Domínguez, Ph.D., UTEP professor of clinical laboratory science (CLS) and co-investigators Wen-Yee Lee, Ph.D., UTEP associate professor of chemistry, and Maria E. Alvarez, Ph.D., professor and coordinator of biology and chemistry programs at EPCC’s Transmountain Campus. The Edward N. and Margaret Marsh Foundation funded the study.
EPCC students identified the bacteria isolated from the water and sediment. UTEP’s chemistry department conducted a chemical analysis to determine which antibiotics were present in the river. Fuentes and the CLS program collaborated to identify antibiotic resistance genes found in bacteria. The study found that antibiotics were in 92% of both water and sediment samples gathered from the Rio Grande. Genes conferring resistance were recovered from all collection sites. Of the isolated bacteria, 64% were resistant to at least two synergistic antibiotic combinations and 15% were found to be resistant to 20 or more individual antibiotics.
“This project indeed involved different expertise and resources to study a very complex and unstudied issue on antibiotics and antibiotic resistance in our region,” Lee said. “The project required researchers from biology, chemistry and health sciences to provide a better understanding of what antibiotics (are in the water) and to what extent they have impacted our region.”
Fuentes said antibiotics have found their way into the Rio Grande through animal and human waste and discharge from wastewater treatment plants, which do not have the capability to filter medications out of the water after they’ve been flushed down the toilet. Bacteria can develop antibiotic resistance after being exposed to drugs in the water, as part of a process of natural selection which, according to the study, may lead to an increased number and severity of infections, frequency of treatment failure, allergies and alteration of intestinal flora if people come in direct contact with the water. Despite these findings, researchers suggest more studies are needed to determine the risk of the river’s water quality to public health. In the meantime, Dominguez hopes to raise awareness about the use and misuse of antibiotics and antimicrobial resistance in the border region.
“Other studies show that antibiotic-resistant bacteria have been found in rivers all over the world, not just the Rio Grande,” Dominguez said. “But we still need to study the impact on public health. We need to conduct surveys and do testing in the community. But very minimum concentrations of antibiotics are not good at all in the river because they may impact the microflora we have.”
