Comparative study of the etiology of nosocomial bacteremic pneumonia in ventilated and non-ventilated patients: a 10-year experience in an institution

ABSTRACT The etiology of nosocomial pneumonia (NP) in non-mechanically ventilated patients [hospital-acquired pneumonia (HAP)] is poorly understood because of difficulties in obtaining reliable respiratory samples. While it is thought to resemble that of mechanically ventilated patients [ventilator-associated pneumonia (VAP)], few studies compare etiology in both groups. We compared the etiology of bacteremic NP (bNP) episodes in HAP and VAP over 10 years in our institution. We defined NP in adults according to the American Thoracic Society criteria. bNP episodes were defined as significant isolates in ≥1 blood culture concordant with ≥1 respiratory pathogen isolated with 40%. IMPORTANCE This study on bacteremic nosocomial pneumonia (bNP) demonstrates the importance of this condition both in patients undergoing and not undergoing mechanical ventilation. Staphylococcus aureus, Enterobacterales, and non-fermenting Gram-negative bacilli are all causative agents in ventilator-associated pneumonia (VAP) and hospital-acquired pneumonia (HAP), with a predominance of S. aureus in HAP and of Pseudomonas aeruginosa in VAP. Mortality in this condition is very high. Therefore, new therapeutic and preventive approaches should be sought.