Resistance, heteroresistance and fitness costs drive colistin treatment failure during <i>Acinetobacter baumannii</i> pneumonia.

ABSTRACT: Acinetobacter baumannii is an ESKAPE pathogen linked to healthcare-associated diseases. Due to evolved resistance, last-resort antibiotics such as the lipooligosaccharide (LOS)-targeting colistin are increasingly used to treat multidrug-resistant isolates. To track the evolution of colistin resistance within a host, we performed sequential oropharyngeal infections in immunocompetent or immune-depleted mice in the presence of inhaled colistin. Both resistant and heteroresistant A. baumannii strains emerged with pmrB mutations that efficiently competed with the susceptible parent in the presence of colistin. These pmrB mutants had a fitness cost in the absence of colistin treatment but retained their ability to colonize the host. In contrast, LOS-deficient A. b

SUBMITTER: Hernandez-Bird J 

PROVIDER: S-EPMC12330716 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature