Left untreated, pneumonia, an infection of the lower respiratory tract, is potentially life-threatening. Worldwide, pneumonia is responsible for the mortality of more than 4 million people -- higher than any other infectious disease.1 Thankfully, laboratory tests (among other clinical diagnostics tools) can help detect organisms causing pneumonia so that patients can be treated before symptoms take a turn for the worst.
Laboratory testing for organisms that cause pneumonia has greatly evolved over the years. "Beyond making a diagnosis from clinical symptoms, such as presenting with a fever and cough, radiological findings and physical examination results, medical professionals can now diagnose the illness with the aid of nucleic acid amplification tests, antigen detection, serology and culture," explained Yvette McCarter, PhD, D(ABMM), director of the Clinical Microbiology Laboratory at Shands Jacksonville (Fla.). Detection provides information on the organism causing or associated with that type pneumonia.
A New Wave of Tests
Traditionally, laboratory professionals had to mostly rely on standard microbiological tests of sputum and blood cultures, notes Thomas M. File Jr., MD, MSc, MACP, FIDSA, FCCP, chair, infectious disease division, Summa Health System, Akron, Ohio. "But over the past decade or so, use of molecular tests has increased, a trend which should have a significant impact on the management of this very common and serious infection," File says. "This is an exciting time from this standpoint because these new methods allow the potential for point-of-care diagnosis and the more definitive use of antimicrobial agents with the promise for better care and outcomes of our patients."
Norman Moore, PhD, director of scientific affairs, Infectious Disease, Alere, Waltham, Mass., developed urinary antigen tests for Legionella and Streptococcus pneumoniae. "I felt that, if an immunochromatographic lateral flow test could be developed so that the test was easy and fast enough to affect treatment, the medical community would get a far bigger impact from it," he recalled. After the assay was developed and successfully implemented, the team turned their attention to the most common cause of community-acquired pneumonia (CAP) -- S. pneumonia -- and developed another urinary antigen test. Even after being featured on the covers of The New York Times and The Wall Street Journal, "we still faced the hurdle of educating doctors about what the test could do for better patient outcomes, and physicians continued to call for it to be done in the lab," Moore remembered.
In the U.S. there are about 5 million cases of CAP each year and an additional 250,000-350,000 cases of hospital-acquired pneumonia. "Severity and outcome depend on a lot of different factors, including the infecting organism, the overall health of the patient and how soon they seek medical care," noted McCarter, who is also a professor of Pathology at the University of Florida College of Medicine-Jacksonville. "Patients with underlying medical conditions, especially those affecting the lungs, individuals with compromised immune systems, the very young and the very old are likely to be the most at risk for infection in general."
Because of high mortality rates and people's susceptibility to it, the need for rapid, reliable testing methods to diagnose pneumonia is key. "The availability of rapid testing for respiratory tract pathogens has led to improved patient outcomes," McCarter said. "If a physician is able to determine the organism causing a patient's infection rapidly, it can save a patient from unnecessary testing." These tests can also keep patients from receiving needless antibiotics or having them prescribed sooner when needed.
Correct Collection, Transfer and Storage
No matter what the method of collection or type of specimen, making sure laboratory professionals follow proper collection, transfer and storage guidelines is important to making a correct diagnosis. "The results for all tests performed in microbiology are reliant on the collection of an appropriate specimen," McCarter stressed. "This includes an appropriate volume of specimen collected from the appropriate site prior to the implementation of antibiotic therapy. When good specimens are collected, then good results can be generated and vice versa."
Moore gave the following guidelines for different kinds of specimens:
- Swabs: Need to remain moist and be plated within four hours. If not, they need to be put into transport media and not frozen.
- Sputum: "The patient should be asked to give a deeply-coughed specimen with care being taken to avoid saliva," Dr. Moore noted. The sample then needs to be put into a sterile container and immediately transported to the laboratory.
- Blood culture: Collect two sets about an hour apart.
- Urine: Can be stored at room temperature up to 24 hours, refrigerated for two weeks, or frozen for longer.
The future of pneumonia testing seems open and promising, with many different assays and methods paving the way to better patient outcomes.
"I see nucleic acid amplification testing continuing to expand, both in the organisms detected as well as the availability and ease of use for laboratorians," McCarter said.
"This is an exciting time regarding the emergence of molecular testing for diagnostics of etiology of infectious diseases," added File, who is also a professor of Internal Medicine, master teacher and chair of Infectious Disease Section, Northeast Ohio Medical University, Rootstown. "As these tests become increasingly available, are easy to perform and cost-effective, I envision they will greatly enhance our ability to provide optimal care for our patients. Ultimately, it will be our patients who benefit.
Amanda Koehler is a freelance writer. Contact: email@example.com
- "Pneumonia." Lab Tests Online. http://labtestsonline.org/understanding/conditions/pneumonia/. Last accessed Nov. 28, 2012.