The problem, the consequences, and rapid testing solutions
Since the original description of Legionnaires’ disease in 1977, Legionella pneumophila has been increasingly recognized as a cause of sporadic and epidemic community-acquired pneumonia (CAP) in all age groups.1
L. pneumophila is the third or fourth most frequent pathogen in CAP with a high incidence of admission to the ICU. It is also an important nosocomial pathogen because the hospital setting provides particularly susceptible populations.
Clinical manifestations are not useful in predicting the likelihood of Legionnaires’ disease.2 Conventional microbiology methods have limitations reducing their sensitivity, while the failure of serological testing to diagnose the disease in the acute phase limits its potential to affect clinical decision making.3
According to the IDSA/ATS CAP guidelines, empiric treatment of L. pneumophila is recommended using a macrolide or respiratory fluoroquinolone for every patient with community-acquired pneumonia. In one study, 11.2% of patients with L. pneumophila pneumonia received inappropriate empirical antibiotic therapy at hospital admission.
Significantly, inappropriate empirical antibiotic therapy has been associated with early failure and higher mortality in patients with CAP.4
Rapid, effective diagnosis and treatment reduces Legionellosis-associated mortality. Making a diagnosis of Legionella allows the practitioner to more accurately define the choice and duration of antimicrobial therapy.5 High rates of initial discordant antimicrobial treatment for Legionnaires’ disease may be overcome by regular urine antigen testing for L. pneumophila in all hospitalized patients.6
The BinaxNOW® Legionella urine antigen test provides results in just 15 minutes. Importantly, it provides highly sensitive results from the first few days of disease and its reliability is not affected by prior antibiotic administration.3 The BinaxNOW® Legionella Urinary Antigen Card can be read visually or with the Alere™ Reader*, soon to be DIGIVAL™.
The urine antigen test is now the most common method used to make the diagnosis of Legionnaires’ disease.7 Some doctors have recommended the use of the urinary antigen test for all patients with CAP who require hospitalization.4 Its ease of use and rapidity mean that targeted therapy can be initiated immediately following a positive result instead of using empirical broad-spectrum antibiotic therapy.2
*Only available in select markets.
- Carratalà, J. and Garcia-Vidal, C. An update on Legionella. Current Opinion in Infectious Diseases 2010 23:152–157.
- Yu V. L. and Stout J. E. Community-Acquired Legionnaires’ Disease: Implications for Under-diagnosis and Laboratory Testing. Clinical Infectious Diseases 2008; 46:1365–7
- Kanavaki, S. et al. Laboratory Diagnosis of Legionnaires’ Disease in Patients with Community Acquired Pneumonia (CAP). Pneumon 2003 16(1): 181-188.
- Viasus, D. et al. Community-Acquired Legionella pneumophila Pneumonia. A Single-Center Experience With 214 Hospitalized Sporadic Cases Over 15 Years. Medicine. Volume 92, Number 1, January 2013
- Hollenbeck, B., Dupont, I. and Mermel, L.A. How often is a work-up for Legionella pursued in patients with pneumonia? A retrospective study. BMC Infectious Diseases 2011, 11:237
- von Baum, H. et al. Community-Acquired Legionella Pneumonia: New Insights from the German Competence Network for Community Acquired Pneumonia. Clinical Infectious Diseases 2008 46:1356–64.
- Yu, Stout. Rapid Diagnostic Testing for Community-Acquired Pneumonia. Can Innovative Technology for Clinical Microbiology Be Exploited? CHEST 2009, 136:6