Detection of Legionella Species in Clinical Samples: Comparison of Polymerase Chain Reaction and Urinary Antigen Detection Kits

Abstract

Recently, two excellent methods have been used for the diagnosis of Legionnaires' disease: urinary antigen detection and PCR. The purpose of the present study is to analyze and evaluate the sensitivity and specificity of three different urinary antigen detection kits as well as PCR. A total of 148 samples were collected from 33 patients between 1993 and 2004. These consisted of 73 urine samples obtained from 33 patients, 57 serum samples provided by 29 patients, and 18 respiratory tract specimens from 13 patients. Three commercially available kits were used to detect urinary antigen. For the 5S PCR reaction, primers L5SL2 and L5SR84 were used. Positive results were shown in all patients' urine (representing 79.5% of total samples) using the Binax EIA kit, in 93.9% patients (representing 75.3% samples) using the Binax NOW immunochromatographic kit, and in 90.9% (representing 72.6% samples) using the Biotest EIA kit. Urine samples from 12.1% patients (representing 6.8% of total samples), serum samples from 41.4% patients (representing 35.1% of total samples), and respiratory samples from 84.6% patients (representing 88.9% of total samples) showed positive results with PCR. In testing urine of legionellosis patients, it was suggested that three kits were all valuable tools for diagnosis of legionellosis. Since over one-third of patients' serum samples and most respiratory specimens showed positive results with PCR, the addition of PCR for testing of these samples might be useful, particularly in cases of culture negative and serum antibody negative patients.