It is often very difficult to distinguish between a respiratory infection that is caused by a virus and one which is caused by a bacteria. This is an important distinction because a viral infection will not respond to the commonly used antibiotics whereas a bacterial infection usually will.
On August 30, 1999 the U.S. Food and Drug Administration (the FDA) cleared for marketing a simple, quick, first-of-a-kind urine test for detecting Streptococcus pneumoniae (S. pneumoniae), one of the bacteria that is a leading cause of pneumonia.
The laboratory test, made by Binax, Inc., of Portland, Maine, provides results in 15 minutes. The new test is meant to be used after consideration of a patient's symptoms. The aim of the test is to rule in S. pneumoniae as the probable cause of the pneumonia. The test results can enable a probable diagnosis to be made quicker so treatment can be started sooner with the appropriate antibiotics to combat the S. pneumoniae.
To do the test, a swab is dipped into a urine specimen, removed and inserted into a special test device. The test detects S. pneumoniae antigen in the urine of infected patients within 15 minutes. A positive result indicates that the patient most likely has pneumococcal pneumonia. Results should be confirmed with lab culture of the bacteria.
Conventional methods for diagnosing pneumonia, primarily using sputum or blood, are lengthy and require from two to three days up to several weeks. These conventional tests are often complex and the results are not always reliable. The new test is much quicker, more reliable and easier to use.
The FDA's clearance of the Binax test was based on results of clinical studies in hospitals and outpatient clinics conducted by the manufacturer at seven sites in the U.S. The studies included consideration of substances in the urine that might interfere with test results and also the possible effects on the test results of the pneumococcal vaccination (against pneumonia due to S. pneumoniae).
The Binax test was found to be 93 percent accurate in detecting S. pneumoniae when it was performed on urine samples from 373 patients known to have pneumococcal pneumonia. It was 78 percent accurate when performed on urine from 215 patients who had typical symptoms of pneumonia but may not have had the disease. Test results were not reliable in people who had been vaccinated for pneumonia within the past five days.
The new test can be done in the doctor's office while the patient is there. It may be of special value to people with asthma and to older people. This is because asthma can be triggered and complicated by respiratory infection. And older people tend particularly to be plagued by pneumococcal pneumonia.
The test is by design limited in its scope. It can help in detecting the bacterium S. pneumoniae but it does not detect other bacteria nor does it detect viruses capable of causing pneumonia.
Within these confines it is hoped that this test will contribute to better health care. It is novel, simple, quick and, yes, painless!