Community-Acquired Legionella pneumophila Pneumonia

Abstract

Legionella pneumophila has been increasingly recognized as a cause of community-acquired pneumonia (CAP) and an important public health problem worldwide. We conducted the present study to assess trends in epidemiology, diagnosis, clinical features, treatment, and outcomes of sporadic community-acquired L. pneumophila pneumonia requiring hospitalization at a university hospital over a 15-year period (1995–2010). Among 3934 nonimmunosuppressed hospitalized patients with CAP, 214 (5.4%) had L. pneumophila pneumonia (16 cases were categorized as travel-associated pneumonia, and 21 were part of small clusters). Since the introduction of the urinary antigen test, the diagnosis of L. pneumophila using this method remained stable over the years (p = 0.42); however, diagnosis by means of seroconversion and culture decreased (p < 0.001 and p = 0.001, respectively).The median age of patients with L. pneumophila pneumonia was 58.2 years (SD 13.8), and 76.4% were male. At least 1 comorbid condition was present in 119 (55.6%) patients with L. pneumophila pneumonia, mainly chronic heart disease, diabetes mellitus, and chronic pulmonary disease. The frequency of older patients (aged >65 yr) and comorbidities among patients with L. pneumophila pneumonia increased over the years (p = 0.06 and p = 0.02, respectively). In addition, 100 (46.9%) patients were classified into high-risk classes according to the Pneumonia Severity Index (groups IV–V). Twenty-four (11.2%) patients with L. pneumophila pneumonia received inappropriate empirical antibiotic therapy at hospital admission. Compared with patients who received appropriate empirical antibiotic, patients who received inappropriate therapy more frequently had acute onset of illness (p = 0.004), pleuritic chest pain (p = 0.03), and pleural effusion (p = 0.05). The number of patients who received macrolides decreased over the study period (p < 0.001), whereas the number of patients who received levofloxacin increased (p < 0.001). No significant difference was found in the outcomes between patients who received erythromycin and clarithromycin. However, compared with macrolide use during hospital admission, levofloxacin therapy was associated with a trend toward a shorter time to reach clinical stability (median, 3 vs. 5 d; p = 0.09) and a shorter length of hospital stay (median, 7 vs. 10 d; p < 0.001).Regarding outcomes, 38 (17.8%) patients required intensive care unit (ICU) admission, and the inhospital case-fatality rate was 6.1% (13 of 214 patients). The frequency of ICU admission (p = 0.34) and the need for mechanical ventilation (p = 0.57) remained stable over the study period, but the inhospital case-fatality rate decreased (p = 0.04). In the logistic regression analysis, independent factors associated with severe disease (ICU admission and death) were current/former smoker (odds ratio [OR], 2.96; 95% confidence interval [CI], 1.01–8.62), macrolide use (OR, 2.40; 95% CI, 1.03–5.56), initial inappropriate therapy (OR, 2.97; 95% CI, 1.01–8.74), and high-risk Pneumonia Seve...

Rainfall Is a Risk Factor for Sporadic Cases of Legionella pneumophila Pneumonia

“…However, clinical and laboratory parameters have shown low sensitivity and/or specificity. Although our understanding of CAP caused by Legionella has improved substantially in recent years due to new diagnostic and treatment strategies, a recent study conducted by our group [26] showed that 11.2% patients with LP received inappropriate empirical antibiotic therapy at hospital admission. However, the overall proportion of patients who received inappropriate empirical antibiotic therapy at hospital admission remained stable over the years (from 1995 through 2010).…”

Current and Emerging Legionella Diagnostics for Laboratory and Outbreak Investigations

“…(10,(137)(138)(139). In addition, despite the sensitivity of L. pneumophila to commonly available antibiotics, LD is associated with greater CAP severity and a higher case-fatality rate (up to ϳ30%) than CAP from other atypical pathogens (121,(140)(141)(142)(143)(144)(145). The U.S. LD case-fatality rate has decreased steadily since the mid-1980s (125), from a high of ϳ34% to 8% on average in the 2000s (15).…”

“…The UAT has dramatically outpaced other laboratory methods for diagnosis, representing 82% and 97% of the diagnostic tools used for LD confirmation in Europe and the United States, respectively (15,125,144,146,257). The popularity and ubiquity of the UAT are attributed to its speed, relatively low cost, uncomplicated procedure, ease of sample collection, commercial availability, and FDA clearance (CE marking in the European Union).…”

The Influence of Programmed Cell Death in Myeloid Cells on Host Resilience to Infection with Legionella pneumophila or Streptococcus pyogenes

“…The first pathogen, L . pneumophila , infects lung macrophages and remains confined to the lung [45,47,48] [46,75], while the second pathogen S . pyogenes spreads systemically [67] [35] [68] [69].…”

“…pneumophila infection remains confined to the lung under most circumstances where it causes a severe pneumonia [45] [46]. This bacteria is found in contaminated water supplies, such as air-conditioning systems, and infects alveolar macrophages [45,47,48] [46]. It can cause complications in people with immunosuppression or other health problems, making it an important hospital-acquired infection [49] [50].…”