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Updated: Apr 1, 2026
Murine Oropharyngeal Aspiration Model of Ventilator-associated and Hospital-acquired Bacterial Pneumonia
Published on: June 28, 2018
The impact of onset time on the isolated pathogens and outcomes in ventilator associated pneumonia
Raymond Khan1, Hasan M Al-Dorzi1, Hani M Tamim2
1Intensive Care Department, King Saud bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City Riyadh, Saudi Arabia.
Abstract:
Several guidelines base the empirical therapy of ventilator-associated pneumonia (VAP) on the time of onset. However, there is emerging evidence that the isolated microorganisms may be similar regardless of onset time. This study evaluated the characteristics and outcomes of VAP with different onset times. All of the mechanically ventilated patients admitted to the ICU of a 900-bed tertiary-care hospital between 01/08/2003 and 31/12/2010 were prospectively followed for VAP development according to the National Healthcare Safety Network criteria. The patients were categorized into four groups: EO if VAP occurred within 4 days of intubation and hospital admission; LO if VAP occurred after 4 days of admission; EL if VAP occurred within 4 days of intubation, but after the fourth hospitalization day; and LL if VAP occurred after the fourth day of intubation and hospitalization. Out of the 394 VAP episodes, 63 (16%) were EO episodes, 331 (84.0%) were LO episodes, 40 (10.1%) were EL episodes and 291 (73.1%) were LL episodes. The isolated microorganisms were comparable among the four groups, with a similar rate of potentially multidrug resistant organisms in the EO-VAP (31.7%), LO-VAP (40.8%), EL-VAP (37.5%) and LL-VAP (43.3%) samples. The hospital mortality was 24% for EO-VAP cases, 28% for LO-VAP cases, 40% for EL-VAP cases and 49% for LL-VAP cases. However, in the adjusted multivariate analysis, neither LO-VAP, EL-VAP nor LL-VAP was associated with an increased risk of hospital mortality compared with EO-VAP (OR, 0.86 95% CI, 0.34-2.19; 1.22; 95% CI, 0.41-3.68, and 0.95; 95% CI, 0.43-2.10, respectively). In this study, the occurrence of potential multidrug resistant pathogens and the mortality risk were similar regardless of VAP timing from hospital admission and intubation. The bacterial isolates obtained from the VAP cases did not follow an early vs. late-onset pattern, and thus, these terms may not be clinically helpful.
Insights
Ventilator-associated pneumonia (VAP) onset timing does not significantly impact the types of bacteria or mortality risk. Early versus late VAP classification may not be clinically useful for guiding treatment decisions.
Area of Science:
- Critical Care Medicine
- Infectious Diseases
- Hospital Epidemiology
Background:
- Empirical therapy for ventilator-associated pneumonia (VAP) often relies on onset timing.
- Emerging evidence suggests microbial patterns in VAP may be consistent regardless of onset.
- This study investigates VAP characteristics and outcomes based on different onset times.
Purpose of the Study:
- To evaluate the characteristics and outcomes of VAP based on distinct onset times.
- To determine if early versus late onset influences microbial profiles and mortality.
- To assess the clinical utility of classifying VAP by onset time.
Main Methods:
- Prospective follow-up of mechanically ventilated ICU patients for VAP development.
- Classification of VAP episodes into four groups based on days from intubation and hospitalization.
- Analysis of isolated microorganisms and hospital mortality rates across VAP onset groups.
Main Results:
- Microorganism profiles and rates of multidrug-resistant organisms were comparable across all VAP onset groups.
- Unadjusted hospital mortality rates varied, but adjusted analysis showed no increased mortality risk for late-onset VAP.
- Bacterial isolates did not exhibit a clear early versus late-onset pattern.
Conclusions:
- VAP onset timing from hospital admission and intubation did not correlate with different pathogens or mortality risk.
- The distinction between early-onset and late-onset VAP may lack clinical significance.
- Current classification of VAP by onset time might not be a helpful determinant for empirical therapy.
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