Carbapenem-resistance oprD mutations reshape Pseudomonas aeruginosa host-pathogen interactions during infection.

Antibiotic resistance is a major global health threat. While its role in reducing drug susceptibility is well established, the broader consequences of resistance mutations on bacterial physiology and phenotype during infection remain poorly understood. Carbapenem-resistant Pseudomonas aeruginosa is considered among the highest-priority bacterial threats, with resistance commonly driven by loss-of-function mutations in the carbapenem uptake porin OprD. Here we show that such mutations can arise in clinical isolates even without prior carbapenem treatment, suggesting that their biological impact during infection is not limited to antibiotic resistance. Consistent with this, we found that oprD mutants exhibit enhanced early attachment to and translocation across airway epithelial barriers in an in vitro human infection model, an effect observed across strains with distinct clinical genomic backgrounds and infection dynamics. Our findings indicate that loss of OprD alters the bacterial outer membrane charge and reduces mucus entrapment, thereby facilitating epithelial barrier colonization. Overall, these results illustrate how antibiotic resistance mutations can directly shape infection dynamics, extending their impact well beyond antimicrobial susceptibility.