Introduction

Effective disinfection is crucial for hygiene and infection prevention, but phenotypic heterogeneity, particularly in heterogeneous tolerance, may lead to disinfection failure and foster resistance evolution to both disinfectants and antibiotics. However, the consequences of phenotypic heterogeneity for disinfection outcome & resistance evolution are not well understood.

Goals

This study investigates the impact of phenotypic heterogeneity on E. coli survival and evolution during disinfection with six commonly used substances and exploring the consequences of evolved disinfectant tolerance for antibiotic resistance.

Materials & Methods

Population heterogeneity is assessed through time-kill kinetics and mathematical modeling, with a link to the evolvability of disinfectant tolerance examined through periodic disinfection evolution experiments. The ability of disinfectant-tolerant strains to evolve antibiotic resistance is evaluated through serial transfer experiments and whole-genome sequencing.

Results

Multi-modal time-kill kinetics in three disinfectants suggest the presence of disinfectant-tolerant subpopulations (persister cells). Notably, strains with disinfectant tolerance show a reduced likelihood of developing high-level resistance to specific antibiotics compared to the sensitive ancestor, indicating a distinct antibiotic-specific outcome. WGS reveals epistatic interactions between disinfectant tolerance & antibiotic resistance mutations, preventing access to canonical evolutionary paths to resistance.

Summary

Our findings suggest that phenotypic heterogeneity can facilitate disinfection survival & the evolution of population wide tolerance, which can impact future antibiotic resistance evolution.