By Marcus Gay, NM WRRI Student Program Coordinator
Kimberly McNair is a graduate student in the Department of Biology at New Mexico Institute of Mining and Technology (NMT) and is expecting to graduate in the spring of 2020 with a Master of Science degree. Last year she received a New Mexico Water Resources Research Institute (NM WRRI) Student Water Research Grant entitled, Tracking CRE in the Rio Grande: determining correlation between the appearance of antibiotic resistant bacteria in surface waters and local infection rates. The focus of McNair’s research is to uncover how the Rio Grande influences the spread of antibiotic resistance genes throughout the state of New Mexico.
Antibiotic resistance is a global health threat. Resistant infections are often acquired from healthcare settings due to frequent use of common antibacterial agents, but environmental factors likely play a role in transmission. Contamination of natural waterways via human activity can introduce pathogens to the surrounding area and downstream communities. Carbapenem-resistant Enterobacteriaceae (CRE) is an emerging group of antibiotic resistant microbes. Carbapenems are often used as a last line of defense to fight otherwise resistant bacterial infections and multiple studies have suggested that CRE can be present in surface waters.
McNair states, natural water sources can be contaminated by runoff or treated wastewater, carrying dangerous bacteria to previously unexposed populations. While these organisms may cause infection, they often have the ability to transfer resistance and virulence related genes to other bacteria in the surrounding environment. By tracking the appearance of certain antibiotic resistance genes over time, it may be possible to better understand where contaminants originate, and what role they play in causing disease. McNair is working on potentially establishing a link between contaminants and disease by comparing the genes carried by bacteria recovered from the Rio Grande to those found in local infections. If the river does play a role in spreading disease between communities, action may be taken to mitigate future risk.
For this project, water samples from the Rio Grande are filtered and examined for antibiotic resistance genes. Specifically, genes that convey resistance to carbapenems will be sought out. Water samples are collected every two months to check for any seasonal differences. Sudden changes in the water, such as the introduction of new genes, would indicate that the river has been contaminated by a new source, likely upstream of the sample site. Any bacteria found containing genes of interest will be sent off for DNA sequencing to determine its species. The observed organisms in the river will be compared to infection data from the New Mexico Department of Health. Correlation between bacteria or genetic elements from the environment and from hospitalized patients would suggest that the Rio Grande is involved in spreading infectious bacteria.
Results of the study indicate that two carbapenem resistance genes have been found in the Rio Grande: VIM and IMP. VIM and IMP had been recovered in water samples, but they have not yet appeared in clinical infections through 2017. The appearance of these genes in the environment may precede future clinical reports. The sources of these contaminants are unknown, however, demonstrating the presence of IMP on a mobilizable genetic element in the Rio Grande would have significant implications for how CRE spreads in New Mexico surface waters. Carbapenem resistance itself can spread between organisms, and prevalence of CRE in the river may increase. The dissemination of resistant bacteria and, by conjunction, carbapenem-resistance genes, would be harmful to the health and economic well-being of nearby residents.
As McNair explains, “It is important for us to know how our environment can spread disease, especially through important environmental resources like water.” McNair presented the results of her research at the NM WRRI 64th Annual New Mexico Water Conference, and the American Society of Microbiology Conference.
McNair, originally from Colorado Springs, received her bachelor’s degree in Biology from NMT. McNair is working on this project under the guidance of Dr. Linda DeVeaux, an Associate Professor and the Biology Department Chair at NMT. After graduation, McNair hopes to continue her work in microbiology, possibly working in industry with a focus on pathogens, epidemiology, or public health.