A highly sensitive laboratory test that uses gold nanoparticles caught my interest. The need for accuracy has allowed DNA laboratory tests for genetics and infectious diseases to become the standard of care. But, when it comes to infectious diseases, speed and ease of use can make a test much more valuable.
Each year, over 12 million patients will seek emergency room treatment for flu symptoms. These patients may spend hours in the ER and 200,000 will eventually be hospitalized. One concern of respiratory viruses is pandemic influenza control. Historical data shows that rapid tests used to detect outbreaks in institutions play an important role in controlling pandemic influenza.
Researchers have developed the Verigene System, which uses DNA probes that coat the molecules of interest with gold nanoparticles, allowing for the rapid detection of a single respiratory virus at the genetic level. Tissue cultures had been the standard for respiratory virus detection in the past. Since then, PCR assays offered higher sensitivity and specificity for the detection of respiratory virus. The disadvantage is it is still a slow process that takes hours for results.
I asked Alejandro C. Arroliga, MD, FCCP, FACP, director of the Division of Pulmonary and Critical Care Medicine at Scott & White Hospital, and professor of Medicine at Texas A&M Health Science Center College of Medicine in Temple, TX, about how critical time is when diagnosing a respiratory virus. He stated, There are several existing methods to determine if an infection is viral or bacterial, such as a culture or PCR. But, these are expensive and they do not give you an answer right away. You can do PCR but first, you have to take a swab and send it to the lab and there are costs involved with sending it to a lab. The results come in one to two days. Because of the time element, we do not always do a laboratory test for a respiratory virus.
Clinical trials showed that using gold nanoparticles offered 98.0% sensitivity and 96.5% specificity for respiratory viruses such as RSV and influenza, including the H1N1 strain. The same trial also detected respiratory viruses in 58% of specimens that were negative in tissue culture tests.
Now, with a rapid diagnosis of a respiratory virus, physicians will have more information to better manage patient’s illnesses, which will translate to reduced antibiotic usage, correct use of influenza antiviral drugs, and a reduced length of stay in a hospital emergency department. If anything, the 2009 H1N1 pandemic is a prime example of the need for a five-minute test that does not require sample preparation. Gold nanoparticles may sound catchy but the results are what matters.