Background: We compared the etiology of 203 ICU-acquired laboratory confirmed bloodstream infections (LC-BSI) prospectively collected between January 2000-December 2007 (first period) with 83 LC-BSI recorded between January 2010-December 2012 (second period), after the diffusion in 2008 of K. pneumoniae expressing carbapenem-resistance due to K. pneumoniae carbapenemases production (KPC-CR-Kp).
Methods: In the general ICU of teaching hospital "Umberto I" in Rome, all ICU-acquired LC-BSI episodes occurring in patients admitted to ICU≥48h were included. Baseline characteristics, clinical features, antimicrobial resistance and outcome were recorded. All isolated strains multidrug resistance (MDR) were evaluated according to the European Centre for Disease Control (ECDC) guidelines.
Results: Overall the study included 329 isolates, 214 in 2000-2007 and 115 in 2010-2012. In the second period we registered a Gram-positive reduction (55.1% vs. 26.9%; P<0.01) and Gram-negative increase (40.2% vs. 69.6%; P<0.01). In 2000-2007 staphylococci were responsible for 45.8% LC-BSI's, whereas 18.3% during 2010-2012. Enterobacteriaceae increased dramatically (15.4% vs. 39.2%; P<0.01), especially Klebsiella spp. (5.6% vs. 31.3%; P<0.01). LC-BSI associated mortality decreased among Gram-positive (56.8% vs. 51.6%), but increased in Gram-negative (41.9% vs. 60.0%; P<0.03), especially in Enterobacteriaceae (RR 2.13; 95% CI 1.21 - 3.73; P<0.01). MDR increased remarkably among Enterobacetriaceae (51.5% vs. 73.3%). The study highlighted the associated mortality for Enterobacteriaceae when comparing MDR to non-MDR microorganisms.
Conclusion: ICU-acquired LC-BSI etiology shifted from Gram-positive to Gram-negative during the study period in our ICU. Also associated mortality decreased among the former, whereas it increased in the latter. Last MDR increased enormously among Enterobacteriaceae with the diffusion of KPC (75% of strains), adding significantly to associated mortality (RR 2.17; 1.16-4.05; P<0.01).