USAGE OF URINARY ANTIGEN TEST FOR LEGIONELLA

USAGE OF URINARY ANTIGEN TEST FOR LEGIONELLA ON DIAGNOSED COMMUNITY-ACQUIRED PNEUMONIA IN SAN ANTONIO HOSPITALS

Abstract

Despite advances in medium formulations and pretreatment techniques, recovery of Legionella from water samples can still be quite low, difficult and time consuming. The aim of this study was to evaluate the utility of a Legionella urinary antigen enzyme immunoassay (Bartels ELISA, Trinity Biotech, Ireland) for the detection of Legionella in water samples. Reference ATCC Legionella strains were used to spike water samples to a final concentration of 104-105 cfu/ ml. The lower detection limit of the test for all Legionella pneumophila serogroups was assessed by serial dilutions of spiked water samples. Legionella antigen was detected in all filtered samples except for those spiked with L. bozemanii and L. longbeachae. The lower detection limit for soluble L. pneumophila serogroup 1 antigen was 780 cfu/ml. Bartels ELISA could be a useful method for antigen detection in water samples when a high recovery of L. pneumophila is suspected. The test could be used as a rapid screening method for the detection of Legionella in a large number of samples. However, the low sensitivity of the test requires to keep on performing conventional culture for isolation and for further studies on isolated bacteria

USAGE OF URINARY ANTIGEN TEST FOR LEGIONELLA ON DIAGNOSED COMMUNITY-ACQUIRED PNEUMONIA IN SAN ANTONIO HOSPITALS

Introduction

Legionella pneumophila is a recognized pathogen causing both community-acquired and nosocomial pneumonia (Bartlett et al., 2000; Mandell, 2000; Ruef, 1998; Stout and Yu, 1997). Water is the major reservoir for Legionella, and although these bacteria are found in freshwater environments worldwide, legionellosis disease has emerged because of human alteration of the environment (Fields et al., 2002). Water systems in buildings are often contaminated with Legionella and therefore serve as amplifiers of the bacteria, representing a source of outbreaks and sporadic infection.

Hospitals represent ideal locations for legionnaires' disease transmission: at-risk patients, plumbing systems are frequently old and water temperatures are often reduced to prevent scalding of patients. Over the last years, several large outbreaks linked to cooling towers and other water systems have been described (Fields et al., 2002). The control of colonization in cooling towers and other aerosol-generating devices can reduce community outbreaks of legionnaires' disease (Fields et al., 2002). In addition, the control of hot water system colonization in hospitals is crucial to prevent Legionella infection in patients at-risk (Ruef, 1998). Despite advances in medium formulations and pretreatment techniques, recovery of Legionella from water samples can still be quite low, difficult and time consuming (Edelstein, 1987).

In addition, although there is an international consensus guideline for culture detection and enumeration of Legionella in water (International Organization for Standardization, 1998), the overgrowth of other accompanying bacteria and the presence of viable but non-culturable Legionella have not been fully resolved (Steiner et al., 1997). Thus, there is a need for improved detection methods. Urinary antigen testing has been proven rapid, sensitive and specific in diagnosing legionellosis (Domi´ nguez et ...