Pneumococcal pneumonia: differences according to blood culture results

Bacteremia by Streptococcus pneumoniae has been traditionally associated with poor outcomes in patients with pneumonia; however, data on its impact on outcomes are limited and are sometimes contradictory.

We performed a prospective study in two hospitals in northern Spain in which cases diagnosed with pneumococcal pneumonia were selected from a cohort of hospitalized patients with pneumonia between January 2001 and July 2009. We compared patients with pneumococcal bacteremic pneumonia with those with pneumococcal non-bacteremic pneumonia.

We compared 492 patients with negative blood culture and 399 with positive culture results. Host related factors were very similar in both groups. Severity of illness on admission measured by CURB-65 score was similar in both groups. Adjusted analysis showed a greater likelihood of septic shock during in-hospital course among patients with pneumococcal bacteremia (OR, 2.1; 95% CI, 1.2-3.5; P=0.006). Likewise, patients with positive blood culture had greater in-hospital mortality (OR 2.1; 95% CI, 1.1- -3.9; P=0.02), 15-day mortality (OR 3.6; 95% CI, 1.7-7.4; P=0.0006), and 30-day mortality (OR, 2.7; 95% CI, 1.5-5; P=0.002).

Although host related factors and severity on admission were very similar in the two groups, bacteremic patients had worse in-hospital course and outcomes. Bacteraemia in pneumococcal pneumonia is of prognostic significance.