Acute Inflammatory Response of Patients with Pseudomonas aeruginosa Infections: A Prospective Study

The severity of Pseudomonas aeruginosa (PA) infection may be determined by the interaction with the host immune system. We designed a prospective study to assess the relationship between the inflammatory response and the clinical presentation and outcome of PA infection. We also investigated whether there are differences in the inflammatory response depending on the resistance profile of PA. Interleukin-6 (IL-6), IL-10, procalcitonin (PCT), and C-reactive protein (CRP) were measured. Sixty-nine infection episodes were recorded; 40 caused by non-multidrug-resistant (non-MDR) strains [29 (73%) respiratory; 8 (20%) bacteremia], 12 by MDR non-extensively drug-resistant (MDR-non-XDR) [9 (75%) respiratory; 3 (25%) bacteremia], and 17 by XDR strains [9 (53%) respiratory; 7 (41%) bacteremia]. All inflammatory parameters were significantly higher in patients who developed acute organ dysfunction and bacteremia. PCT levels were higher in patients with early mortality [p = 0.050]. Inflammatory biomarkers were higher in patients with XDR than in those with non-MDR PA [IL-6 430 (67-951) vs. 77 (34-216), p = 0.02; IL-10 3.3 (1.5-16.3) vs. 1.3 (0-3.9), p = 0.02; and PCT 1.1 (0.6-5.2) vs. 0.3 (0.1-1.0), p = 0.008]. The intensity of inflammatory response was associated with the severity of PA infection, particularly if bacteremia occurred. Only PCT was documented useful to predict the outcome. XDR infections presented a higher inflammatory response; related in part to the larger number of bloodstream infections in this group.