The role of gram-negative bacteria in healthcare-associated pneumonia

Healthcare-associated pneumonia (HCAP) is a unique entity that differs from community-acquired pneumonia in both bacteriology and outcomes and has similarities to hospital-acquired pneumonia and ventilator-associated pneumonia. HCAP patients are at higher risk of potential multidrug-resistant pathogens, including resistant gram-negative organisms, especially Pseudomonas aeruginosa and Acinetobacter spp., but also extended-spectrum β-lactamases (ESBLs). This manuscript reviews the epidemiology, etiology, and clinical outcomes of hospitalized HCAP patients due to gram-negative bacteria. We will focus our attention on the potential multidrug-resistant pathogens to suggest a new treatment approach for these patients.