A Fast Test to Diagnose Flu

Hazi, A U

关键词: ADENOVIRUS;    ANTIBIOTICS;    CHAIN REACTIONS;    DEFEROXAMINE;    INFECTIOUS DISEASES;    INFLUENZA;    MEDICAL ESTABLISHMENTS;    PATHOGENS;    PHYSICS;    POLYMERASE CHAIN REACTION;    SYMPTOMS;    VIRUSES;   

DOI  :  10.2172/902892
RP-ID  :  UCRL-TR-228196
PID  :  OSTI ID: 902892
Others  :  TRN: US200720%%330

美国|英语

来源: SciTech Connect

【 摘 要 】

People with flu-like symptoms who seek treatment at a medical clinic or hospital often must wait several hours before being examined, possibly exposing many people to an infectious virus. If a patient appears to need more than the routine fluids-and-rest prescription, effective diagnosis requires tests that must be sent to a laboratory. Hours or days may pass before results are available to the doctor, who in the meantime must make an educated guess about the patient's illness. The lengthy diagnostic process places a heavy burden on medical laboratories and can result in improper use of antibiotics or a costly hospital stay. A faster testing method may soon be available. An assay developed by a team of Livermore scientists can diagnose influenza and other respiratory viruses in about two hours once a sample has been taken. Unlike other systems that operate this quickly, the new device, called FluIDx (and pronounced ''fluidics''), can differentiate five types of respiratory viruses, including influenza. FluIDx can analyze samples at the point of patient care--in hospital emergency departments and clinics--allowing medical providers to quickly determine how best to treat a patient, saving time and potentially thousands of dollars per patient. The FluIDx project, which is led by Livermore chemist Mary McBride of the Physics and Advanced Technologies Directorate, received funding from the National Institute of Allergy and Infectious Diseases and the Laboratory Directed Research and Development (LDRD) Program. To test the system and make it as useful as possible, the team worked closely with the Emergency Department staff at the University of California (UC) at Davis Medical Center in Sacramento. Flu kills more than 35,000 people every year in the US. The 2003 outbreak of severe acute respiratory syndrome and the ongoing concern about a possible bird flu pandemic show the need for a fast, reliable test that can differentiate seasonal flu from a potentially pandemic influenza. Such a test should also discriminate influenza from pathogens that cause illnesses with flu-like symptoms. When a precise diagnosis is required to treat an adult patient with serious respiratory symptoms, sample cells are usually obtained with a nasal or throat swab and analyzed with one of several laboratory methods. The gold standard test is viral culturing, a highly sensitive method that can identify the specific strain of virus. However, viral culturing is a labor-intensive process and requires 3-10 days to produce results, too long for early intervention. Enzyme and optical immunoassays offer results in 30 minutes, but these methods are less sensitive than viral culturing so they can produce false positives or negatives. They also cannot distinguish the type of virus found. Direct immunofluorescence antibody (DFA) staining is as sensitive as viral culturing. It also can detect multiple respiratory pathogens simultaneously by a process known as multiplexing. However, DFA staining requires expensive equipment, a skilled microscopist, and samples with enough target cells for testing. In addition, the results are ultimately subjective. Another method, called reverse transcriptase-polymerase chain reaction assay, offers sensitivity and specificity comparable to viral culturing and DFA staining. It also produces results in two hours and can rapidly test a large number of samples. The drawback with these tests, however, is that they must be performed in a laboratory. None of them can be used where they are needed most: in the clinic or emergency department where patients are being treated. Livermore's FluIDx diagnostic system, with its instrumentation and multiplexed assays, is designed specifically for point-of-care diagnosis. The fast, easy-to-use system is based on the Autonomous Pathogen Detection System, a homeland security technology developed by LLNL. This R&D 100 Award-winning technology constantly monitors the air to detect airborne bioterrorism agents, such as anthrax. FluIDx is an integrated system designed to perform highly multiplexed polymerase chain reaction (PCR) nucleic-acid-based assays in real time. The FluIDx system processes a sample, analyzes the data, reports the results, and decontaminates itself before another sample is taken. The device currently uses 16 assays--12 for individual nucleic-acid targets and 4 for internal controls. The assays can simultaneously detect influenza A and B, parainfluenza (Types 1 and 3), respiratory syncytial virus, and adenovirus (Groups B, C, and E).