Antimicrobial resistant pathogens display significant public health threats by causing difficulties in clinical treatment of bacterial infection. Antimicrobial resistance (AMR) is transmissible between bacteria, significantly increasing the appearance of antimicrobial resistant pathogens, aggravating the AMR problem. In this work, the dissemination dynamics of AMR from invading multidrug resistant (MDR) Escherichia coli to a community of pathogenic Salmonella enterica was investigated using a continuous culture device, and the behaviors of dissemination dynamics under different levels of antibiotic stress were investigated. Three MDR E. coli invasion events were analyzed in this work: MDR E. coli-S. enterica co-colonization, MDR E. coli invasion after antibiotic treatment of S. enterica, and MDR E. coli invasion before antibiotic treatment of S. enterica. It was found that both horizontal gene transfer (HGT) and vertical gene transfer (VGT) play significant roles in AMR dissemination, although different processes contribute differently under different circumstances; that environmental levels of antibiotics promote AMR dissemination by enhancing HGT rather than leading to selective advantage for resistant bacteria; and that early invasion of MDR E. coli completely and quickly sabotages the effectiveness of antibiotic treatment. These findings contribute to understanding the drivers of AMR dissemination under different antibiotic stress, the detrimental impact of environmental tetracycline contamination, and the danger of nosocomial presence and dissemination of MDR non-pathogens.
IMPORTANCE
Antimicrobial resistance poses a grave threat to public health and reduces the effectiveness of antimicrobial drugs in treating bacterial infections. Antimicrobial resistance is transmissible, either by horizontal gene transfer between bacteria, or by vertical gene transfer following inheritance of genetic traits. The dissemination dynamics and behaviors of this threat, however, hasn’t been rigorously investigated. In this work, with a continuous culture device, we studied antimicrobial resistance dissemination processes by simulating antimicrobial resistant Escherichia coli invasion to a pathogenic Salmonella enterica community. Using this novel tool, we provide evidence on the drivers of antimicrobial resistance dissemination, on the detrimental impact of environmental antibiotic contamination, and on the danger of antimicrobial resistance in hospitals, even if what harbors the antimicrobial resistance is not a pathogen. This work furthers our understanding on antimicrobial resistance and its dissemination between bacteria, and on antibiotic therapy, our most powerful tool against bacterial infection.