Detection of Legionella antigenuria by reverse passive agglutination

A reverse passive agglutination method was developed to detect soluble antigens of Legionella spp. By this method Legionella antigens were detected in urine specimens from 14 of 15 antigenuric patients with clinically diagnosed Legionnaires disease and in none of 263 urine samples from healthy subjects or patients with urinary tract infections. Intra-genus cross-reactivity was observed only between L. pneumophila serogroups 2, 3, and 6. The Legionella reverse passive agglutination method was also evaluated with reference to reagent concentrations, test conditions, and subjectivity of reading test results. The method is rapid and does not require special equipment.