Clinical outcomes of Pseudomonas aeruginosa pneumonia in intensive care unit patients.

Purpose: Our aim was to identify the clinical profile of intensive care unit (ICU) patients with Pseudomonas aeruginosa (PA) pneumonia and the impact on ICU mortality and duration of mechanical ventilation (MV) of multidrug resistance (MDR) in the PA isolate and inadequate initial antibiotic therapy (IIAT).

Methods: We conducted a retrospective analysis of data prospectively collected in the 18-bed general ICU of a major teaching hospital in Rome, Italy. The study cohort consisted of 110 adult patients with culture-confirmed PA pneumonia consecutively diagnosed in 2008-2010. ICU survivor and nonsurvivor groups were compared to identify factors associated with ICU mortality.

Results: In 42 (38 %) of the 110 cases of PA pneumonia analyzed, the PA isolate was MDR. Fifty-six (50.9 %) of the patients received IIAT, and 49 (44.5 %) died in ICU. In logistic regression analysis, IIAT, diabetes mellitus, higher Simplified Acute Physiology Score (SAPS) II scores, and older age were independently associated with ICU mortality. Among survivors, those who received IIAT or had MDR PA pneumonia had significantly longer median (interquartile ranges, IQR) periods of post-pneumonia onset MV (16.5 [14.5-20] and 15 [12-18] days, respectively) compared with those whose initial therapy was adequate (8 [6-13] days, P < 0.001) and those whose infections were caused by non-MDR PA (10.5 [6.5-13] days, P = 0.01).

Conclusions: Our findings highlight the importance of IIAT as a risk factor for mortality in ICU patients with PA pneumonia. MDR in the PA isolate, like IIAT, can significantly increase the need for MV.