Abstract
BackgroundLegionnaires’ disease (LD) is associated with high mortality rates and poses a diagnostic and therapeutic challenge. Use of the rapid urinary antigen test (UAT) has been linked to improved outcome. We examined the association between the method of diagnosis (UAT or culture) and various clinical and microbiological characteristics and outcome of LD.MethodsConsecutive patients with pneumonia and confirmation of Legionella infection by a positive UAT and/or a positive culture admitted between the years 2006–2012 to a university hospital were retrospectively studied. Isolated L. pneumophila strains were subject to serogrouping, immunological subtyping and sequence-based typing. Variables associated with 30-day all-cause mortality were analyzed using logistic regression as well as cox regression.ResultsSeventy-two patients were eligible for mortality analyses (LD study group), of whom 15.5 % have died. Diagnosis based on positive L. pneumophila UAT as compared to positive culture (OR = 0.18, 95 % CI 0.03–0.98, p = 0.05) and administration of appropriate antibiotic therapy within 2 hospitalization days as compared to delayed therapy (OR = 0.16, 95 % CI 0.03–0.90, p = 0.04) were independently associated with reduced mortality. When controlling for intensive care unit (ICU) admissions, the method of diagnosis became non-significant. Survival analyses showed a significantly increased death risk for patients admitted to ICU compared to others (HR 12.90, 95 % CI 2.78–59.86, p = 0.001) and reduced risk for patients receiving appropriate antibiotic therapy within the first two admissions days compared to delayed therapy (HR 0.13, 95 % CI 0.04–0.05, p = 0.001). Legionella cultures were positive in 35 patients (including 29 patients from the LD study group), of whom 65.7 % were intubated and 37.1 % have died. Sequence type (ST) ST1 accounted for 50.0 % of the typed cases and ST1, OLDA/Oxford was the leading phenon (53.8 %). Mortality rate among patients in the LD study group infected with ST1 was 18.2 % compared to 42.9 % for non-ST1 genotypes (OR = 0.30, 95 % CI 0.05-1.91, p = 0.23).ConclusionsThe study confirms the importance of early administration of appropriate antibiotic therapy and at the same time highlights the complex associations of different diagnostic approaches with LD outcome. Infection with ST1 was not associated with increased mortality. Genotype effects on outcome mandate examination in larger cohorts.
Highlights
Legionnaires’ disease (LD) is associated with high mortality rates and poses a diagnostic and therapeutic challenge
Patients and outcome During the study period, 83 patients were identified with positive Legionella culture (26 patients), positive urinary antigen test (UAT) test (44 patients) or both (13 patients) (Fig. 1)
Seventy one adult patients were eligible for LD mortality analysis, and will be referred to as the LD study group
Summary
Legionnaires’ disease (LD) is associated with high mortality rates and poses a diagnostic and therapeutic challenge. We examined the association between the method of diagnosis (UAT or culture) and various clinical and microbiological characteristics and outcome of LD. Legionella pneumonia, known as Legionnaires’ disease (LD), is characteristically a disease of middle age and elderly patients, and may be associated with a high mortality rate [3, 4]. Legionella spp. are resistant to beta-lactam antibiotics, which constitute the most commonly prescribed agent for patients with pneumonia. Appropriate antibiotic therapy may be often delayed, especially if Legionella is not a priori considered the etiologic agent. Another obstacle for the timely administration of appropriate therapy is delayed diagnosis. Serologic studies mostly require paired samples obtained two weeks apart [8] and largely have been abondoned in recent years
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call