Legionnaires' disease at a Dutch flower show: prognostic factors and impact of therapy

Abstract

After a large outbreak of Legionnaires' disease in the Netherlands, we determined risk factors for intensive care unit (ICU) admission and death and the impact of adequate therapy on ICU-free survival among 141 hospitalized patients. Overall mortality rate was 13%, and ICU mortality rate was 36%. Smoking, temperature >38.5 degrees C, and bilateral infiltrates shown on chest x-ray were independent risk factors for ICU admission or death (all p<0.05). Starting adequate therapy within 24 hours after admission resulted in a higher ICU-free survival rate compared to therapy initiation after 24 hours: 78% versus 54%, respectively (p=0.005). However, delay in providing therapy to patients with urinary antigen tests with negative results did not influence outcome. These data suggest that by using the urinary antigen test on admission a more tailored approach to patients with community-acquired pneumonia may be applied.

Figure 1

Patient disposition and selection. ICU, intensive care unit.

Figure 2

Kaplan-Meier curve for intensive care unit (ICU)–free survival. ICU-free survival for patients treated with adequate antibiotics within and >24 h after admission.:___ adequate antibiotic therapy started within 24 h after admission (n=85); ----- adequate antibiotic therapy started >24 h after admission (n=56).

Figure 3

Survival curves and urinary antigen test results. A: Intensive care unit ICU)–free survival for patients with a positive or negative urinary Legionella antigen test (Binax Now, Binax, Portland, ME):___ negative urinary antigen test (n=51); ----- positive urinary antigen test (n=86). B: ICU-free survival for patients with a negative urinary Legionella antigen test (Binax Now):___ adequate antibiotic therapy started within 24 h after admission (n=38); ----- adequate antibiotic therapy started more than 24 h after admission (n=13). C: ICU-free survival for patients with a positive urinary Legionella antigen test (Binax Now): ___ adequate antibiotic therapy started within 24 h after admission (n=.46); ----- adequate antibiotic therapy started >24 h after admission (n=40).