Detection of Aspergillus fumigatus DNA
Aspergillus fumigatus is considered the most prevalent airborne fungal pathogen that causes severe and often fatal invasive aspergillosis (IA) among immunocompromised individuals such as patients with leukemia or those who have undergone organ transplantation. Aspergillus is a ubiquitous environmental hyaline mold that is responsible for a spectrum of disease. Clinical syndromes range from non-invasive colonization such as aspergilloma (fungal ball) and allergic responses such as allergic bronchopulmonary aspergillosis (ABPA), to semi-invasive and invasive disease including necrotizing pneumonia, invasive pulmonary aspergillosis, and disseminated invasive aspergillosis involving tissue. Aspergillus fumigatus is the most frequently isolated species and is most commonly associated with invasive infection. Diagnosing these infections relies upon accurately recognizing a constellation of clinical signs and symptoms, as well as imaging and laboratory studies. These diagnoses are difficult, expensive, and time consuming. In the laboratory, culture of invasive fungal pathogens is slow and can be complicated by the presence of contaminating molds in the environment, and Aspergillus spp. are rarely if ever isolated from blood culture. Further, in many specimens from patients, fungal organisms can be seen by microscopy of tissue sections or body fluids, but are not viable. Some specimens may never reveal the presence of a fungal pathogen because of low abundance and/or lack of viability.
A rapid test with high sensitivity and specificity for detecting A. fumigatus DNA in clinical specimens is required for successful antifungal therapy.
Internal Transcribed Spacer sequence exhibit species-specific polymorphisms suitable for distinguishing A. fumigatus from other fungi including genetically closely related species such as Neosartorya ficheri. A nested PCR protocol with A. fumigatus specific FRET probes is employed to achieve high sensitivity and specificity.
The Aspergillus fumigatus DNA detection by PCR [ASPDNA] allows the rapid detection of Aspergillus fumigatus using primers and Aspergillus fumigatus sequence-specific probes designed to bind to the internal transcribed spacer of the rRNA operon. Fluorescence detection utilizes a FRET hybridization probe and a TaqMan hydrolysis probe specific for Aspergillus fumigatus. Real-time PCR is used to detect DNA extracted directly from clinical specimens facilitating more rapid detection of fungal elements.
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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