Rapid Urine Test Detects Bacteria Causing Pneumonia

By LabMedica International staff writers
Posted on 29 Sep 2014

A simple, quick, first-of-a-kind urine test for detecting Streptococcus pneumoniae, one of the bacteria that are a leading cause of pneumonia, can also be used with cerebral spinal fluid (CSF) of patients with meningitis.

The aim of the test is to rule in S. pneumoniae as the probable cause of the pneumonia and 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.

Image: The BinaxNOW Streptococcus pneumoniae Antigen Card Test (Photo courtesy of Alere).

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 laboratory 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, called Alere BinaxNOW Streptococcus pneumoniae Antigen Card (Binax, Inc.; Portland, ME, USA) is much quicker, more reliable and easier to use.

The Binax test was found to be 93% accurate in detecting S. pneumoniae when it was performed on urine samples from 373 patients known to have pneumococcal pneumonia. It was 78% accurate when performed on urine from 215 patients who had typical symptoms of pneumonia, but may not have had the disease. However, test results were not reliable in people who had been vaccinated for pneumonia within the past five days. The urine test’s sensitivity was 86% and specificity was 94%, while for CSF samples the sensitivity was 97% and specificity 99%.

It is often very difficult to distinguish between a respiratory infection that is caused by a virus and one which is caused by a bacterium and this is critical distinction because a viral infection will not respond to the commonly used antibiotics whereas a bacterial infection usually will. The Binax test can help in detecting the bacterium S. pneumoniae but it does not detect other bacteria nor does it detect viruses capable of causing pneumonia.

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Binax, Inc.