A study published in nature communications <Link> demonstrated that the within-host diversity of pathogen populations plays a key role in shaping the emergence of resistance in response to treatment. This in contrast to the traditional view that antimicrobial resistance emerges from pathogens that acquire new mutations.
Source: IDSE, July 17, 2023. Link.
“Study results suggest patients are commonly coinfected by multiple pathogen clones, with resistance emerging because of selection for preexisting resistant clones, rather than new mutations.”