Decreased Risk of Ventilator-Associated Pneumonia in Sepsis Due to Intra-Abdominal Infection

Rationale
Experimental studies suggest that intra-abdominal infection (IAI) induces biological alterations that may affect the risk of lung infection.
Objectives
To investigate the potential effect of IAI at ICU admission on the subsequent occurrence of ventilator-associated pneumonia (VAP).
Methods
We used data entered into the French prospective multicenter Outcomerea database in 1997–2011. Consecutive patients who had severe sepsis and/or septic shock at ICU admission and required mechanical ventilation for more than 3 days were included. Patients with acute pancreatitis were not included.
Measurements and Main Results
Of 2623 database patients meeting the inclusion criteria, 290 (11.1%) had IAI and 2333 (88.9%) had other infections. The IAI group had fewer patients with VAP (56 [19.3%] vs. 806 [34.5%], P<0.01) and longer time to VAP (5.0 vs.10.5 days; P<0.01). After adjustment on independent risk factors for VAP and previous antimicrobial use, IAI was associated with a decreased risk of VAP (hazard ratio, 0.62; 95% confidence interval, 0.46–0.83; P<0.0017). The pathogens responsible for VAP were not different between the groups with and without IAI (Pseudomonas aeruginosa, 345 [42.8%] and 24 [42.8%]; Enterobacteriaceae, 264 [32.8%] and 19 [34.0%]; and Staphylococcus aureus, 215 [26.7%] and 17 [30.4%], respectively). Crude ICU mortality was not different between the groups with and without IAI (81 [27.9%] and 747 [32.0%], P = 0.16).
Conclusions
In our observational study of mechanically ventilated ICU patients with severe sepsis and/or septic shock, VAP occurred less often and later in the group with IAIs compared to the group with infections at other sites.