Nosocomial Pneumonia in the Intensive Care Unit Acquired by Mechanically Ventilated versus Nonventilated Patients

Rationale Most current information on hospital-acquired pneumonia (HAP) is extrapolated from patients with ventilator-associated pneumonia (VAP). No studies have evaluated HAP in the intensive care unit (ICU) in nonventilated patients. Objectives: To compare pneumonia acquired in the ICU by mechanically ventilated versus nonventilated patients. Methods: We prospectively collected 315 episodes of ICU-acquired pneumonia. We compared clinical and microbiologic characteristics of patients with VAP (n = 164; 52%) and nonventilator ICU-acquired pneumonia (NV-ICUAP; n = 151; 48%). Among NV-ICUAP patients, 79 (52%) needed subsequent intubation. Measurements and Main Results: Compared with NV-ICUAP, patients with VAP were more severe (APACHE-II 17 +/- 6 vs. 15 +/- 5; P <0.001) and pneumonia occurred later in the ICU (8 +/- 8 vs. 5 +/- 6 d; P < 0.001). Etiologic diagnosis (117, 71% vs. 64, 42%; P < 0.001), nonfermenting (28% vs. 15%; P = 0.009) and enteric gram-negative bacilli (26% vs. 13%; P = 0.006), and methicillin-sensitive Staphylococcus aureus (14% vs. 6%; P = 0.031) were more frequent in VAP, likely caused by more patients with lower respiratory tract samples cultured (100% vs. 84%; P < 0.001). However, in patients with defined etiology only, the proportion of pathogens was similar befween groups, except for a higher proportion of Streptococcus pneumoniae in NV-ICUAP (P = 0.045). The hospital mortality also was similar. Conclusions: Despite a lower proportion of pathogens in NV-ICUAP compared with VAP, the type of isolates and outcomes are similar regardless of whether pneumonia is acquired or not during ventilation, indicating they may depend on patients' underlying severity rather than previous intubation. With the diagnostic techniques currently recommended by guidelines, both types of patients might receive similar empiric antibiotic treatment.