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Updated: Aug 7, 2026

Implementation of In Vitro Drug Resistance Assays: Maximizing the Potential for Uncovering Clinically Relevant Resistance Mechanisms
Published on: December 9, 2015
The probability of treatment induced drug resistance
1University of Colorado, Colorado Springs, USA. schinazi@math.uccs.edu
Abstract:
We propose a discrete time branching process to model the appearance of drug resistance under treatment. Under our assumptions at every discrete time a pathogen may die with probability 1-p or divide in two with probability p. Each newborn pathogen is drug resistant with probability mu. We start with N drug sensitive pathogens and with no drug resistant pathogens. We declare the treatment successful if all pathogens are eradicated before drug resistance appears. The model predicts that success is possible only if p<1/2. Even in this case the probability of success decreases exponentially with the parameter m=muN. In particular, even with a very potent drug (i.e. p very small) drug resistance is likely if m is large.
Insights
This study models pathogen drug resistance using a discrete time branching process. Treatment success, preventing resistance, is only possible if pathogen division probability (p) is less than 1/2, decreasing exponentially with increased resistance parameters.
Area of Science:
- Mathematical Biology
- Evolutionary Biology
- Pharmacology
Background:
- Drug resistance is a major challenge in treating infectious diseases.
- Understanding the evolutionary dynamics of resistance emergence is crucial for effective treatment strategies.
- Branching processes offer a framework for modeling population growth and extinction events.
Purpose of the Study:
- To develop a mathematical model simulating the emergence of drug resistance in pathogens during treatment.
- To identify conditions under which treatment can be successful before resistance arises.
- To analyze the impact of key parameters on the probability of treatment success.
Main Methods:
- A discrete time branching process model was employed.
- Pathogen dynamics were simulated with probabilities of death (1-p) and division (p).
- Drug resistance in new pathogens was incorporated with probability mu, starting with N sensitive pathogens.
Main Results:
- Treatment success is predicted to be possible only when the pathogen division probability (p) is less than 1/2.
- The probability of successful treatment decreases exponentially as the parameter m (mu*N) increases.
- Drug resistance is likely to emerge even with potent drugs if the parameter m is large.
Conclusions:
- The discrete time branching process model provides insights into the dynamics of drug resistance.
- Treatment success is highly sensitive to pathogen proliferation rates and the initial number/resistance of pathogens.
- Minimizing the parameter m (mu*N) is critical for successful eradication of drug-sensitive pathogens before resistance develops.
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