NMT Biology Grad Student Examining Antibiotic Resistance Genes in Wastewater

By Thomas Guengerich, NM Tech Office of Communications and Marketing

New Mexico Tech graduate student in biology Angelica Cave recently landed a grant from the New Mexico Water Resource Research Institute to support her study of antibiotic resistant bacteria in wastewater treatment.

Her proposal is titled “Antibiotic resistance in wastewater treatment: the effects of different treatment methods on the differential survival of antibiotic resistant pathogens over non-resistant bacteria through the treatment process of two different wastewater treatment plants.”

Cave, along with her advisor Dr. Linda DeVeaux, will collect and examine samples taken from in-coming sewage, the aerobic digester, and the treated wastewater, as well as from the channel the wastewater is discharged into, both upstream and downstream from the Socorro Wastewater Treatment Plant. In addition, collaborators in South Dakota will be providing similar samples for analysis from the Rapid City Wastewater treatment plant, as both areas have similar “interference” from agriculture and livestock, but slightly different treatment processes during the summer months.

“I hope to find out if bacteria carrying antibiotic resistance genes have a better chance of surviving the treatment processes used in the two wastewater treatment plants,” she said. “We’ll be looking primarily at two panels of genes – 7 pathogenicity genes and 10 genes for resistance to beta-lactam antibiotics.”

Cave is taking samples from untreated wastewater, and the aerobic digester‒where the organic material gets broken down and is the most biologically significant step in the treatment process‒as well as treated wastewater. She will determine the presence of antibiotic resistance genes (ARGs) and virulence genes (VGs). The proportion of bacteria carrying ARGs will determine whether the presence of ARGs provides increased survivability to bacteria in the two treatment plants. Cave will take samples multiple times in the next year to see temporal changes, which will allow insight into the dynamics of ARBs in the environment.

Once samples are collected, Cave will conduct two studies: Firstly, she will extract genomic DNA from the original environmental samples and test the DNA for the VGs and ARGs. Secondly, she will culture Gram-negative bacilli from samples showing the genes of interest, to isolate the bacteria that contain those genes. Additionally, she will test isolates of interest to determine if they are resistant to multiple classes of antibiotics.

Cave said this project will provide new information about the possible connections between antibiotic resistance genes and antibiotic resistant bacteria in the environment and wastewater treatment practices. She said this is very important because a link between the spread of ARB and ARGs and wastewater treatment plants has long been suspected and, although it has not been confirmed definitively, there are studies that support this theory, and so more research is greatly needed. Antibiotic resistant infections are becoming an increasing threat to public health and safety, which makes this research timely and important.

Cave said this project has the potential to benefit the Socorro community by providing insight into the presence of antibiotic resistance in the local surface water, which may lead to better antibiotic stewardship practices in the local clinics. She said this sort of community project can raise awareness in our local community and foster further relationships between NMT and the Socorro community.

“Without this grant, it’d be difficult for our lab to afford everything we need for this project,” she said. “I’m really excited to have the opportunity to present this research at the NM WRRI research conference in October.”

An Albuquerque native, Cave started her college career at Central New Mexico Community College. There, she took prerequisite courses for the Diagnostic Medical Sonography program offered at CNM, which exposed her to math and science for the first time.

“I fell in love with biology and chemistry,” she said. “I decided on New Mexico Tech because it had a very similar feel to CNM, with the smaller class sizes and sense of community.”

She earned her bachelor’s in biology at NMT and decided to stay for a master’s degree. She is interested in pursuing a career in public health, specializing on the microbiology of how antibiotic resistance moves through the environment.

“It’s a big unknown,” she said. “We don’t know how wastewater treatment factors into the spread of ARGs in the environment, and I’d like to pursue that question further.”