Phenotype-Guided Nanotherapeutic Strategies for Carbapenem-Resistant Acinetobacter baumannii: Toward Precision...

Carbapenem-resistant Acinetobacter baumannii (CRAB) is considered a persistent clinical problem characterized by high mortality and restricted therapeutic options. The current antimicrobial regimen focuses on active bacteria without taking into account physiological states that influence the treatment response. Biofilm formation, metabolic changes, efflux activity, and membrane remodeling reduce antibiotic activity at infection sites and help bacteria survive despite in vitro susceptibility. Clinical performance is also compromised by inadequate tissue penetration, toxicity, and inconsistent pharmacokinetics, which reduce the ability to maintain effective antimicrobial activity at the target site. Therefore, a new strategy is needed that considers how bacteria behave during infection. Nanotherapeutic systems can optimize antimicrobial delivery by changing drug distribution and enabling sustained antimicrobial release within infected tissues. These properties can improve antimicrobial distribution within biofilms and structurally restricted infection sites. This review proposes a phenotype-guided approach linking dominant bacterial phenotypes with targeted nanotherapeutic intervention. Advances in nanoscale diagnostics and computational analysis allow earlier identification and more precise characterization of resistance features, so treatment decisions reflect the current state of infection. When integrated with nanotechnology, this information supports treatment approaches that adapt to changes in bacterial behavior over time. Extending this concept to host-directed and microbiome-informed interventions provides additional control by addressing factors that sustain infection beyond the pathogen. These elements create an integrated system that connects detection, analysis, and treatment, allowing therapy to match the biological conditions of infection for more precise CRAB management.