Improvement of antibiotic therapy and ICU survival in severe non-pneumococcal community-acquired pneumonia: a matched case-control study

Introduction: We aimed to compare intensive care unit mortality due to non-pneumococcal severe community-acquired pneumonia between the periods 2000-2002 and 2008-2014, and the impact of the improvement in antibiotic strategies on outcomes. Methods: This was a matched case-control study enrolling 144 patients with non-pneumococcal severe pneumonia: 72 patients from the 2000-2002 database (CAPUCI I group) were paired with 72 from the 2008-2014 period (CAPUCI II group), matched by the following variables: microorganism, shock at admission, invasive mechanical ventilation, immunocompromise, chronic obstructive pulmonary disease, and age over 65 years. Results: The most frequent microorganism was methicillin-susceptible Staphylococcus aureus (22.1 %) followed by Legionella pneumophila and Haemophilus influenzae (each 20.7 %); prevalence of shock was 59.7 %, while 73.6 % of patients needed invasive mechanical ventilation. Intensive care unit mortality was significantly lower in the CAPUCI II group (34.7 % versus 16.7 %; odds ratio (OR) 0.78, 95 % confidence interval (CI) 0.64-0.95; p = 0.02). Appropriate therapy according to microorganism was 91.5 % in CAPUCI I and 92.7 % in CAPUCI II, while combined therapy and early antibiotic treatment were significantly higher in CAPUCI II (76.4 versus 90.3 % and 37.5 versus 63.9 %; p < 0.05). In the multivariate analysis, combined antibiotic therapy (OR 0.23, 95 % CI 0.07-0.74) and early antibiotic treatment (OR 0.07, 95 % CI 0.02-0.22) were independently associated with decreased intensive care unit mortality. Conclusions: In non-pneumococcal severe community-acquired pneumonia, early antibiotic administration and use of combined antibiotic therapy were both associated with increased intensive care unit survival during the study period.