Mortality associated with carbapenem-susceptible and Verona Integron-encoded Metallo-β-lactamase-positive Pseudomonas aeruginosa bacteremia.

Background: Studies on various Gram-negative bacteria suggest that resistance to carbapenem antibiotics is responsible for increased mortality in patients; however, results are not conclusive. We first assessed the 28-day in-hospital all-cause mortality in patients with Verona Integron-encoded Metallo-β-lactamase-positive Pseudomonas aeruginosa (VIM-PA) bacteremia compared to patients with VIM-negative, carbapenem-susceptible P. aeruginosa (CS-PA) bacteremia. Second, we identified determinants for mortality and survival.

Methods: All patients with a positive blood culture with VIM-PA or CS-PA between January 2004 and January 2016 were included. Kaplan-Meier survival curves were constructed, and survivors and non-survivors were compared on relevant clinical parameters using univariate analyses, and multivariable analyses using a Cox-proportional hazard model.

Results: In total, 249 patients were included, of which 58 (23.3%) died. Seventeen out of 40 (42.5%) patients with VIM-PA died, compared to 41 out of 209 (19.6%) patients with CS-PA (difference = 22.9%, P-value = 0.001). Assumed acquisition of the bacterium at the intensive care unit was significantly associated with mortality (HR = 3.32, 95%CI = 1.60-6.87), and having had adequate antibiotic therapy in days 1-14 after the positive blood culture was identified as a determinant for survival (HR = 0.03, 95%CI = 0.01-0.06). VIM-PA vs CS-PA was not identified as an independent risk factor for mortality.

Conclusions: The crude mortality rate was significantly higher in patients with a VIM-PA bacteremia compared to patients with a CS-PA bacteremia; however, when analyzing the data in a multivariable model this difference was non-significant. Awareness of the presence of P. aeruginosa in the hospital environment that may be transmitted to patients and rapid microbiological diagnostics are essential for timely administration of appropriate antibiotics. Acquisition of P. aeruginosa should be prevented, independent of resistance profile.