1464. The Clinical Features of Pneumonia Caused by Legionella pneumophila vs. Streptococcus pneumoniae: A Retrospective Study

Abstract

BackgroundLegionnaires’ disease (LD) is a serious and often lethal pneumonia caused by Legionella bacteria. From 2001 to 2016, the incidence of Legionnaires’ disease has tripled in the United States. The clinical manifestations of pneumonia caused by L. pneumophilia (LP) may be similar to those caused by Streptococcus pneumoniae (SP). As mortality from Legionella pneumonia is high (15–50%), an investigation of factors that differentiate these two types of pneumonia is required.Methods(1) To determine the clinical features that differentiate community-acquired pneumonia (CAP) caused by LP SG 1 vs. SP; and (2) to assess outcomes associated with CAP caused by LP serogroup 1 vs. SP. W conducted a retrospective chart review of adult patients admitted between January 1, 2013 and October 31, 2017 for confirmed LP or SP pneumonia. Data were collected on demographic and clinical characteristics, comorbidities, month of admission, laboratory values, vital signs, and outcomes. Data were analyzed using Student’s t-test, the chi-squared test and logistic regression with the forward likelihood ratio algorithm.ResultsOf 106 patients, 48.1% had LP, 64.4% were male, 56.6% were black and the mean age was 59.1 ± 15.3 years. The incidence of LP peaked in the summer. Results of univariable analysis are shown in the table.FactorLPSP P-ValueMean Temp. (°F)102.3 ± 1.799.0 ± 9.00.009Diarrhea50%20.4%0.002Male gender78.4%43.6%<0.0001Median CWIC score0.0 (1–4)1.0 (0–13)0.02Mean Na (mEq/L)130.2 ± 4.6132.1 ± 18.90.5From multivariable analysis, predictors of LP were male gender (OR=18.2, P < 0.0001), diarrhea (OR = 3.7, P = 0.05), BMI (OR = 1.2, P = 0.05) and CWIC score (OR = 0.57, P = 0.004). Patients with SP were more likely to require intubation (P = 0.04), an ICU stay (P = 0.004) and to die (P = 0.002).ConclusionOur data suggest that high temperature and diarrhea may be used to help differentiate LP and SP pneumonia. The higher incidence among men requires further investigation. LP demonstrated a higher morbidity and mortality than SP.Disclosures All authors: No reported disclosures.