How to Manage Pseudomonas aeruginosa Infections

Pseudomonas aeruginosa is a pathogen frequently encountered in healthcare-associated infections and immunocompromised patients. In bacteremia, this pathogen is associated with higher mortality than other Gram-negative pathogens. This increase in mortality was also found globally for multi-resistant compared to susceptible strains. Several factors have been associated with the development of resistance: previous ICU stay, use of carbapenems, and comorbidities were identified in multivariate analysis. In the therapeutic choice, previous antibiotic treatment remains the strongest driver suggesting a potential resistant strain. These risk factors will decide whether multi-resistant strains must be considered in the empiric coverage. For susceptible strains, a single agent can be used, β-lactams are usually the first choice. Associations do not provide any advantage on mortality. Optimization of pharmacokinetic/pharmacodynamic parameters, such as prolonged infusion (for time-dependent antibiotics), increased dosage (for concentration-dependent antibiotics), and therapeutic drug monitoring, also influences the outcome. The increasing number of resistant strains led the clinician to use either recently approved new molecules but also associations. For multi-resistant strains, new molecules such as ceftolozane-tazobactam, ceftazidime-avibactam, and cefiderocol have shown an adequate activity against P. aeruginosa. Older molecules like colistin and fosfomycin are also used in this indication. The complexity of the resistance and consequences on a larger scale of antibiotic prescription will probably lead to more individualized prescriptions.