Prevalence of polymyxin heteroresistance in Klebsiella pneumoniae under sustained antibiotic selection during experimental evolution.

The swift increase in resistance exhibited by Klebsiella pneumoniae, primarily a nosocomial pathogen, against all frontline antibiotics has significantly restricted the available therapeutic options. Additionally, the rising resistance to polymyxins, frequently considered the last-resort antibiotic, has further exacerbated the situation. The molecular mechanisms responsible for developing high levels of polymyxin resistance are well understood.