Clinical impact of bacterial heteroresistance

Bacterial heteroresistance is defined when a seemingly susceptible population of bacteria contains one or more resistant subpopulations. This behaviour has been seen in a variety of bacteria and with many different antibiotics. Heteroresistance is largely unrecognized during clinical diagnosis, because it is hard to accurately test for in a clinical lab using standard antibacterial test methodologies. Overlooking heteroresistance may contribute to inaccurate definitions of antibiotic susceptibility and could lead to poorer patient outcomes, undermining global antimicrobial stewardship. Awareness of the clinical impact of heteroresistance should be better represented in antimicrobial susceptibility test guidance, so clinicians can better spot heteroresistance when present and adjust dosing or treatment plans if necessary. Development of viable clinical tests for heteroresistance should be made a research priority, allowing us to better understand, test and treat heteroresistant bacteria.