Molecular Changes in Bacteria after Aerosolization Leading to Antimicrobial Resistance

BROOKE SMITH, Maria King, Texas A&M University

     Abstract Number: 124
     Working Group: Bioaerosols

Abstract
The study of environmental changes triggering antimicrobial resistance (AMR) expression is a growing field, but not much has been studied on how aerosolization effects and triggers AMR. This should be of particular interest for high resistance reservoirs such as hospitals and meat-producing facilities. The goal of this research is to uncover how Gram-negative bacteria respond to aerosolization at a molecular level using the laboratory strain Escherichia coli (E. coli) MG 1655 as surrogate bacterium. Fresh mid-log phase bacterial suspensions were aerosolized for 5 different time durations into a sterile airtight chamber and collected using a bioaerosol collector. Each sample was analyzed based on its response to aerosolization by molecular analysis such as specific antibiotic resistance gene (ARG) expression, genetic sequencing, antibiotic susceptibility testing and molecular dynamics simulations. Strong resistance and binding to efflux pump active sites was detected to cell wall and protein synthesis inhibitors after aerosolization. Resistance to the highest number of antibiotics was detected in the shortest aerosolization samples while exposure for longer aerosolization durations caused an increased amount of stress which bacteria could not alleviate, indicating the involvement of different mechanisms to respond to short-term and long-term exposures. There were also clear phenotypic changes in E. coli cells particularly at the cell membrane. This study aims to demonstrate that aerosolization triggers antimicrobial resistance and show the changes linked to mechanisms of resistance, especially efflux pump regulation, in E. coli.