Heteroresistance as a Stochastic Property of a Dynamical System in Bacterial Populations

Antibiotic resistance is often treated as a fixed genetic trait, yet clinical isolates frequently exhibit heteroresistance—a phenomenon in which only a small subpopulation survives antibiotic concentrations that inhibit the majority. The frequency of these resistant cells can vary continuously across orders of magnitude, challenging the traditional binary classification of “susceptible” or “resistant.” In this talk, I will introduce this phenomenon and describe a quantitative strategy for its detection that captures the full distribution of survival probabilities within a population. I will then discuss our efforts to uncover its underlying mechanism, showing how stochastic fluctuations in cellular physiology generates transiently resistant states that propagate across lineages.