For a study, researchers sought to examine the features and predictors of outcome in patients hospitalized to critical care units with a hospital-acquired bloodstream infection (HA-BSI) caused by a respiratory illness (ICUs). The EUROBACT multicenter cohort trial, which was done in 162 ICUs in 24 countries, was subjected to a post hoc analysis. Candidaemia-related HA-BSIs were ruled out, as were HA-BSIs from a combination of respiratory and nonrespiratory causes. 230 patients with HA-BSI respiratory infections (HA-BSI requiring ICU admission, n=40; ICU-acquired noninvasively ventilated respiratory BSI, n=30; and ICU-acquired invasively ventilated BSI, n=160) were compared to 749 patients with HA-BSI not related to respiratory infections in the EUROBACT study.
HA-BSI respiratory infections were more frequently caused by gram-negative cocci (76.3% vs. 56.7%, P<0.0001), primarily Acinetobacter baumannii (18.3% vs. 10.4%, P=0.0007) and Klebsiella spp. (18.7% vs. 11%, P=0.0013), and were less frequently caused by gram-positive cocci (23.3% vs. 41.2%, P<0.0001), with the exception of Staphylococcus aureus (11.3% vs. 9.5%, P=0.39). When compared to non-respiratory infections, HA-BSI respiratory infections were more commonly linked with multiple drug-resistant bacteria (53.9% vs. 42.7%, P=0.0003), were more prevalent in medical patients, and were more likely to be ICU-acquired. HA-BSI of respiratory origin was shown to be a risk factor for day-28 mortality after adjusting for severity and other risk variables (odds ratio=1.52 [1.02-2.27], P=0.04). Among 230 patients with HA-BSI of respiratory origin, those needing ICU admission had a higher rate of septic shock (24/40=60%) than noninvasively (9/30=30%) or invasively (71/160=44%, P=0.04) ventilated patients. The recovered bacteria from the three groups of HA-BSI from the respiratory tract were identical. When confounding variables were included, the risk of mortality for ICU-acquired HA-BSI occurring among invasively ventilated patients was lower (odds ratio=0.41 [0.19-0.92], P=0.03) than for patients who had not been invasively ventilated prior to HA-BSI of respiratory origin. The multicenter EUROBACT research demonstrated that the lung, as a respiratory source of infection, was linked with more gram-negative resistant pathogens and a worse outcome.
Lung infections in noninvasively mechanically ventilated patients with BSI were linked with greater septic shock and a poorer outcome than patients with bacteremic ventilator-associated pneumonia.