CAREER: A Systematic Understanding of Accelerated Emergence and Transmission of Antibiotic Resistance under Non-antibiotic Micropollutant Exposure

Antibiotic resistance poses a major global threat to public health. The World Health Organization estimates that annual deaths due to antibiotic resistant infections could reach 10 million by 2050 if no actions are taken. Antibiotic-resistant bacteria (ARB) are found in many natural and engineered environments in surface water, soil, and wastewater.

ARB in these environments may enter potable water supply and food chains, resulting in human exposure and increased risk. Thus, it is critical to understand and control the emergence and spread of ARB in these environments to better protect human health. The goal of this CAREER research project is to understand how the presence of micropollutants affects the development, proliferation, and transmission of antibiotic resistance under environmentally relevant conditions.

This will be achieved by specific research to track the induction of antibiotic resistance in microorganisms exposed to micropollutants through a novel combination of chemistry and molecular biology. Successful completion of this research will advance knowledge of how micropollutants induce antibiotic resistance. Results also have strong potential to improve efforts to monitor and prevent the spread of antibiotic resistance.

Dissemination of results to the public on antibiotic resistance issues form the basis of outreach efforts in collaboration with local wastewater treatment plants, high schools, and colleges in the Inland Empire Region of southern California. These efforts will benefit society by educating the public about a critical public health issue and increase the scientific literacy of the Nation.

Although antibiotic resistance selected by increasing concentration of antibiotics has been well studied, there is a critical knowledge gap concerning how the co-occurrence of non-antibiotic micropollutants and antibiotics in the environment influence the development of antibiotic resistance. Preliminary work found that non-antibiotic micropollutants influence the development and transmission of antibiotic resistance in a synergistic manner.

The goal of this CAREER project is to develop a mechanistic understanding of this process specifically focusing on the genotype-to-phenotype relationships that underpin the development and transmission of antibiotic resistance. This goal will be achieved through specific research integrating selective growth experiments with systems and molecular biology tools.

The genetic basis leading to synergistic antibiotic resistance selection will be first identified and validated via molecular biological tools. Next, the environmental factors that promote the proliferation of resistant mutants selected from the co-exposure of antibiotics and non-antibiotic micropollutants will be examined. Short-term growth competition tests will use co-cultures containing two strains of bacteria with different antibiotic resistance capacity.

The fitness of each strain will be assessed during growth using single nucleotide polymorphism (SNP) genotyping. Lastly, the effect of exposure to non-antibiotic micropollutants on conjugative horizontal gene transfer (HGT) will be determined via mating experiments between the same and different bacterial species. The molecular mechanisms leading to accelerated HGT will be identified by comparative transcriptomics and proteomics.

The research program will be integrated with an education and outreach component that emphasizes diversity through activities designed for different groups of learners. Undergraduate workshops (“WeAreIn”) will be organized to encourage participation of women undergraduates in STEM, and research training programs will be utilized for recruiting undergraduates from underrepresented groups.

Online education resources will be developed for K-12, undergraduate, and graduate students, and open houses and a public website will target local communities to educate the public on antibiotic resistance and promote the proper use and disposal of antibiotics to control its spread.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.