O'Donnell JN, et al. - Given carbapenems have demonstrated efficacy in treating nosocomial pneumonias in clinical trials despite a reported low lung penetration compared to other β-lactams, researchers compared carbapenems to other anti-pseudomonal β-lactams, to identify if differences in outcomes exist, potentially as a function of decreased penetration. They used data from clinical trials reporting clinical and microbiologic outcomes associated with treatment and excluded pediatric studies and those with uneven comparators (eg, carbapenem vs combination Gram-negative therapy). Treatment with carbapenems vs non-carbapenem β-lactams resulted in no different clinical outcomes. Those infected with P. aeruginosa fared worse and were more likely to have resistance develop if they were treated with imipenem.