Mortality in ICU patients with bacterial community-acquired pneumonia: when antibiotics are not enough

It remains uncertain why immunocompetent patients with bacterial community-acquired pneumonia (CAP) die, in spite of adequate antibiotics.

This is a secondary analysis of the CAPUCI database which was a prospective observational multicentre study. Two hundred and twelve immunocompetent patients admitted to 33 Spanish ICUs for CAP were analyzed. Comparisons were made for lifestyle risk factors, comorbidities and severity of illness. ICU mortality was the principal outcome variable.

Bacteremic CAP (43.3 vs. 21.1%) and empyema (11.5 vs. 2.2%) were more frequent (P < 0.05) in patients with Streptococcus pneumoniae CAP. Higher rates of adequate empiric therapy (95.8 vs. 75.5%, P < 0.05) were observed in patients with S. pneumoniae CAP. Patients with non-pneumococcal CAP experienced more shock (66.7 vs. 50.8%, P < 0.05), and need for mechanical ventilation (83.3 vs. 61.5%, P < 0.05). ICU mortality was 20.7 and 28% [OR 1.49(0.74-2.98)] among immunocompetent patients with S. pneumoniae (n = 122) and non-pneumococci (n = 90), in spite of initial adequate antibiotic. Multivariable regression analysis in these 184 immunocompetent patients with adequate empirical antibiotic treatment identified the following variables as independently associated with mortality: shock (HR 13.03); acute renal failure (HR 4.79), and APACHE II score higher than 24 (HR 2.22).

Mortality remains unacceptably high in immunocompetent patients admitted to the ICU with bacterial pneumonia, despite adequate initial antibiotics and comorbidities management. Patients with shock, acute renal failure and APACHE II score higher than 24 should be considered for inclusion in trials of adjunctive therapy in order to improve CAP survival.