Al-Jaghbeer MJ, et al. - Researchers undertook this case-case-control study to determine clinical predictors for pneumonia due to Pseudomonas aeruginosa (PA) which is (1) susceptible to all routinely tested antipseudomonal beta-lactams (APBL-S) and (2) resistant to at least one antipseudomonal beta-lactam (APBL-R). They identified stratification of hospitalized patients with pneumonia based on structural lung disease, prior airway colonization and recent antimicrobial exposure as helpful in improving empirical antimicrobial selection. In patients with risk factors for APBL-S or APBL-R PA, they suggest expansion of antimicrobial regimen from ceftriaxone to APBL or combination therapy, respectively.