Related Experiment Video
Updated: Oct 30, 2025
Methodology for the Study of Horizontal Gene Transfer in Staphylococcus aureus
Published on: March 10, 2017
Combining mutation and horizontal gene transfer in a within-host model of antibiotic resistance
M G Roberts1, S Burgess2, L J Toombs-Ruane2
1School of Natural & Computational Sciences, Massey University, Private Bag 102 904, North Shore Mail Centre, Auckland, 0745, New Zealand; New Zealand Institute for Advanced Study, Massey University, Private Bag 102 904, North Shore Mail Centre, Auckland, 0745, New Zealand; Infectious Disease Research Centre, Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand.
Abstract:
Antibiotics are used extensively to control infections in humans and animals, usually by injection or a course of oral tablets. There are several methods by which bacteria can develop antimicrobial resistance (AMR), including mutation during DNA replication and plasmid mediated horizontal gene transfer (HGT). We present a model for the development of AMR within a single host animal. We derive criteria for a resistant mutant strain to replace the existing wild-type bacteria, and for co-existence of the wild-type and mutant. Where resistance develops through HGT via conjugation we derive criteria for the resistant strain to be excluded or co-exist with the wild-type. Our results are presented as bifurcation diagrams with thresholds determined by the relative fitness of the bacteria strains, expressed in terms of reproduction numbers. The results show that it is possible that applying and then relaxing antibiotic control may lead to the bacterial load returning to pre-control levels, but with an altered structure with regard to the variants that comprise the population. Removing antimicrobial selection pressure will not necessarily reduce AMR and, at a population level, other approaches to infection prevention and control are required, particularly when AMR is driven by both mutation and mobile genetic elements.
Insights
Antimicrobial resistance (AMR) can develop in bacteria through mutation or horizontal gene transfer (HGT). Relaxing antibiotic use may not reduce AMR, necessitating alternative infection control strategies.
Area of Science:
- Microbiology
- Mathematical Biology
- Epidemiology
Background:
- Antibiotics are crucial for treating bacterial infections in humans and animals.
- Antimicrobial resistance (AMR) develops via bacterial mutation or horizontal gene transfer (HGT).
Purpose of the Study:
- To model the development of AMR within a single host animal.
- To establish criteria for resistant bacterial strain replacement or co-existence with wild-type strains.
- To analyze the impact of HGT on AMR dynamics.
Main Methods:
- Development of a mathematical model for AMR evolution.
- Derivation of criteria for strain replacement and co-existence using reproduction numbers.
- Analysis of bifurcation diagrams to illustrate bacterial population dynamics.
Main Results:
- Criteria were derived for resistant mutant replacement and co-existence with wild-type bacteria.
- Conditions for exclusion or co-existence of resistant strains were determined for HGT via conjugation.
- Results indicate that relaxing antibiotic pressure may not decrease AMR and can alter bacterial population structure.
Conclusions:
- Removing antimicrobial selection pressure does not guarantee a reduction in AMR.
- AMR dynamics are influenced by bacterial fitness, reproduction numbers, and HGT.
- Integrated infection prevention and control strategies are essential, especially when AMR is driven by mutation and mobile genetic elements.
Related Concept Videos
01:27Horizontal Gene Transfer
01:16Transduction
01:30Development of Antibiotic Resistance
02:18Types of Genetic Transfer Between Organisms
00:57Antibiotic Selection
01:19Conjugation