Legionella pneumophila IgG ELISA

Introducing our new sensitive Legionella pneumophila IgG- and IgM ELISAs

Serological antibody testing is increasingly recognized as a valuable tool for the diagnosis of legionellosis. The detection of antibodies using ELISA method shows higher sensitivity and better characteristics in terms of automation for routine application and objective measurement than immunofluorescence. Moreover it has been shown to be a valuable tool in epidemiological studies.

IBL International introduces its new Legionella pneumophila IgG- and IgM ELISAs for the qualitative determination of antibodies against Legionella pneumophila serovars 1-7 in human serum or plasma (citrate).

Disease background

Legionellosis is a lung disease most commonly caused by Legionella pneumophila serogroup 1 and with two distinct clinical presentations: Legionnaires' disease, a severe form of pneumonia that can be fatal. Pontiac fever is a milder flulike illness.

Legionella is naturally found in stagnant water, especially warm water. Also spas (hot tubs) can become contaminated with Legionella. Legionellosis can be acquired by the inhalation of contaminated aerosols, but it is not contagious (it cannot be passed from person to person).

Detection methods

Commonly used methods for detection of a Legionella infection involve direct detection methods using culturing, direct fluorescent staining or antigen detection in urine and indirect methods which means the assessment of humoral immune response by antibody detection.

Although culturing remains the gold standard for the diagnosis of legionellosis, its sensitivity may be limited for clinical routine application. Direct fluorescent staining is hampered by low and variable sensitivity.

Direct comparison studies

Direct comparison studies showed that the diagnostic performance of IBL´s Legionella pneumophila IgG- and IgM ELISAs is similar to that of currently available Legionella pneumophila IgG- and IgM assays (Tables 1 and 2), and can be summarized as follows:

Table 1
Diagnostic sensitivity and specificity (internal + external) of
IBL´s Legionella pneumophila IgG ELISA is similar to that of a commercially available Legionella pneumophila IgG assay.

(Evocational results were not included in the calculations)

Table 2
Diagnostic sensitivity and specificity (internal + external) of
IBL´s Legionella pneumophila IgM ELISA is similar to that of a commercially available Legionella pneumophila IgM assay.

(Evocational results were not included in the calculations)

Exerpt from the Instructions for Use

Legionellae are aerobic gram-negative facultative intracellular parasites of certain protozoa. They are found in freshwater environments worldwide and can cause respiratory disease (legionellosis) in humans. Legionella was first identified after an outbreak of pneumonia involving delegates of the 1976 American Legion Convention at a Philadelphia hotel. The genus Legionella currently has at least 50 species comprising 70 distinct serogroups. One species of Legionella, L. pneumophila, is the aetiological agent of approximately 90 % of legionellosis cases, and serogroup 1 (Sg1) accounts for about 84 % of these cases.

L. pneumophila multiplies itself at temperatures between 25 and 42 C, with an optimal growth temperature of 35 °C. Legionella thrives in warm, stagnant water in the environment and in artificial systems such as cooling towers, evaporative condensers, hot and cold water systems and spa pools that mimic the natural environment in which the organism thrives. These systems also provide the means by which aerosols/droplets are generated and the organism dispersed into the atmosphere. Legionellosis can be acquired by the inhalation of aerosols containing Legionella bacteria or by micro-aspiration of ingested water contaminated with Legionella. Person-to-person transmission is not thought to be a risk. Legionellosis can appear in two distinct clinical presentations: Legionella pneumonia (Legionnaires’ disease) with an incubation period of approx. 2-10 days (may extend up to 16-20 days) and Pontiac fever (incubation period: normally 12-48 hours).

Legionella pneumonia (Legionnaires’ disease) is a serious form of pneumonia that carries with it a case-fatality ratio of 10-15 %. Legionnaires’ disease patients initially present with cough, fever and nonspecific symptoms including malaise, myalgia and headache. Some patients develop shaking chills, chest pain, diarrhea, delirium or other neurologic symptoms. Extra pulmonary involvement is rare.

The presence of bacteria resp. infection may be identified by:

• Culture
• Urinary antigen detection
• PCR
• Serology: Detection of antibodies by IF, ELISA

Distributed by Tecan, IBL International GmbH.