Detection and identification Legionella pneumophila and other Legionella species
Legionella species are slow growing fastidious gram-negative organisms that are ubiquitous in the environment. Most exposures which lead to human disease are waterborne, primarily due to inhalation of water droplets from contaminated potable water. Inhalation of water droplets containing Legionella can lead to severe lower respiratory infection (pneumonia) known as Legionnaire's disease. While Legionella is a cause of community acquired pneumonia, it can also be acquired from hospital water systems. Certain populations are at particularly high risk of developing this disease, including those with underlying chronic illness with a high mortality rate among immunocompromised patients. Early diagnosis is key to preventing Legionella-associated mortality.
Rapid urinary assays used to detect Legionella are specific only for L. pneumophila serotype 1, while culture methods require special media and Legionella species is often slow to grow. The Legionella DNA detection by PCR [LEGDNA] is a real-time PCR assay targeting 16S rRNA gene followed by sequence analysis which detects and identifies Legionella pneumophila and other Legionella spp.
Legionella PCR testing is a hybridization probe-based real-time PCR assay using Legionella species specific primers and a single molecular beacon probe. Speciation is done by sequence analysis. This assay allows rapid detection and identification of Legionella species.
DNA extraction, nucleic acid purification, polymerase chain reaction (PCR), sequencing
Acceptable specimens are listed below. Please see Molecular Microbiology Specimen Submission for complete specimen collection and handling instructions.
Shipping/Handling
Acceptable Specimens
*Mycobacterium avium complex DNA Detection [MAVDNA] can be ordered on sputum
**Fungal PCR reflex NGS [FUNDNA] and Fungal DNA Detection by PCR (without reflex to NGS) [NRFDNA] may have interference due to some lots of eSwabs which have been found to contain Saccharomyces cerevisiae DNA, resulting in false positive detection. Clinical correlation and/or retesting with a different collection method is advised. The detection of S. cerevisiae from eSwab specimens can interfere with our ability to rule out other fungal DNA.
Unacceptable Specimens
Optimal Quantity:
Please note: We do not need a separate specimen aliquot for each test ordered. Only a single specimen aliquot or block of optimal quantity is necessary for performing multiple tests. If multiple aliquots or blocks of optimal quantity are sent, up to 2 will be pooled.
Fresh tissue is the optimal specimen of choice, as it reduces the chance of introducing exogenous DNA templates or microorganisms during embedding/fixation. Formalin fixation dramatically reduces the sensitivity of the assays due to reduced template yield and quality.
Please see Molecular Microbiology Specimen Submission for complete specimen collection and handling instructions.
UWMC/HMC: Store and send fresh tissue/fluid specimens refrigerated, if specimen storage and transport will exceed 8 hours, freeze at -20°C. Freeze all fresh tissue/fluid specimens at -20°C upon arrival in UW Molecular Microbiology.
UW-MT |
Microbiology, Molecular Diagnostics
206-520-4600 ---------------------------------------- Shipping Address Attn: Molecular Microbiology Performing Lab Address Clinical Microbiology Lab, NW177 |
Contact Information Please e-mail us with any questions or comments you may have. Your inquiry will be answered as soon as possible. email: molmicdx@uw.edu The Molecular Microbiology lab is open from Monday-Friday, 7am-4pm PDT. Billing inquiries and requests for faxed reports can be made to our Client Services Department at (206) 520-4600 or (800) 713-5198. For results or other inquiries, we can be reached by phone at the following numbers:
For assistance during weekends, holidays and after hours, please contact Lab Medicine Resident at (206) 598-6190 |
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