Clinical Relevance of Positive NOWTMLegionellaUrinary Antigen Test in a Tertiary-Care Hospital in Korea

Abstract

The morbidity and mortality of Legionnaires' disease are not established in Korea, because patients with community-acquired pneumonia (CAP) have rarely been investigated for Legionella. An assay for Legionella antigen in urine has been approved as one of the diagnostic criteria of Legionnaires' disease. Binax Now(TM) Legionella Urinary Antigen Test (LUA) was introduced in Asan Medical Center in July 2002. The purpose of this study was to evaluate the clinical relevance of positive LUA. During the 39-month period from July 2002 to September 2005, the medical records of LUA-positive patients were reviewed for demographic findings, laboratory findings, clinical diagnosis, antimicrobial treatment, outcome, and acquisition of infections. Diagnosis of Legionnaires' disease was based on National Nosocomial Infections Surveillance (NNIS) criteria for defining nosocomial pneumonia. Seven (0.3%) of the 2443 patients tested for LUA were positive. All 7 patients were consistent with the diagnostic criteria of Legionnaires' disease; six patients were diagnosed with CAP and one patient was admitted due to nosocomial pneumonia. Six patients were treated with azithromycin or ciprofloxacin but one patient was not treated for Legionella infection. With the report of LUApositive results, a Legionella-targeted treatment was started in two patients and an inappropriate empirical therapy was ceased in one patient. All patients treated with Legionella-targeted treatment improved clinically except one who died of adult respiratory distress syndrome at the first hospital day. Positive LUA is useful in diagnosing Legionnaire's disease at an early stage and in helping to initiate appropriate treatments in a tertiary-care hospital in Korea.