Molecular Test for Legionella pneumophila

A new molecular test for Legionella pneumophila has been introduced. The test has been cleared by the U.S. Food and Drug Administration (FDA).

Called the ProbeTec ET DNA amplified assay for Legionella pneumeophila, the test is from BD Diagnostics (Sparks, MD, USA), a segment of BD (Becton, Dickinson and Company).

Based on BD's proprietary real-time nucleic acid amplification technology, called strand displacement amplification (SDA), the Legionella assay is designed for the detection of L pneumophila (serogroups 1-14) and performs amplification and real-time detection in a one-hour assay format. It is one of several assays under development at BD for the detection of organisms that cause atypical pneumonia. Other assays being submitted to the FDA for the detection of atypical pneumonia pathogens include Chlamydiaceae family and Mycoplasma pneumoniae.

The availability of this assay is a "major advance in diagnostics for this disease,” according to Victor Yu, M.D., professor of medicine at the University of Pittsburgh (PA, USA) and a leading international expert on Legionnaire's disease.

Professor Yu noted that the disease is one of the main causes of community-acquired pneumonia in the United States and also represents one of the most deadly causes. Patients must be on correct therapy from the first day, and a rapid, molecular amplification assay to detect L pneumophila will help this happen. The test also provides an improvement over current diagnostic assays, since culture takes at least three days and the urinary antigen test for L pneumophila (serogroup 1) may miss up to 12-20% of L pneumophila. Overall, the assay could potentially reduce the mortality associated with this disease and decrease antimicrobial resistance, since it would be possible earlier in the disease course to use directed therapy against this organism once it is detected.

Assays for the BD ProbeTec ET System feature homogeneous amplification and real-time detection technology, combining the power of BD proprietary strand displacement amplification (SDA) with an energy transfer (ET) detection method. SDA is a patented isothermal amplification technology capable of generating billions of copies of target molecules from a single DNA or RNA template in just minutes. The system, first marketed in 1998, is the only commercially available real-time DNA amplification assay for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae.




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