WASHINGTON -- Doctors struggling to decide whether a wheezing patient needs antibiotics to treat pneumonia are about to get a simple, 15-minute test to help their diagnosis.
The Food and Drug Administration approved Binax Inc.'s first-of-a-kind pneumonia test Monday. It uses a patient's urine to detect a bacterium called Streptococcus pneumoniae, a leading cause of pneumonia.
The test should help doctors decide more quickly if a patient's pneumonia is caused by that bacteria, and thus what treatment is needed.
That's a crucial decision for today's doctors because of a growing army of "supergerms," bacteria impervious to antibiotics. Just this month, the government announced that infections caused by antibiotic-resistant Strep pneumoniae are on the rise.
Antibiotics have no effect on viruses. They kill only bacteria. But symptoms alone don't let doctors tell if pneumonia is caused by a virus or bacteria. Conventional pneumonia tests analyze either phlegm or blood and can take two to three days to more than a week. Consequently, doctors often prescribe antibiotics to be safe -- the best decision for a patient with bacterial pneumonia but an unnecessary exposure to antibiotics for patients whose pneumonia was caused by a virus.
Why is that a problem? Unnecessary use of antibiotics leads other bacteria in the body to evolve resistance to the drugs. That could mean that if the patient were to contract a bacterial infection later, antibiotics might not help.
Binax's new pneumonia test detects an antigen, or protein, present on bacterial cells that gets into patients' urine soon after symptoms appear. The antigen acts as a marker for strep-caused pneumonia.
Doctors simply stick a swab into a patient's urine sample and put it on a special reactive strip that within 15 minutes signals if it detects the strep antigen.
"It's a very rapid test, you can get results back quickly," said FDA clinical test chief Dr. Steven Gutman. Pneumonia is "a hard diagnosis," he added, so easy, quick results "certainly are a main advantage."
Binax tested 373 patients already proven to have strep-caused pneumonia, and the new test was 93 percent accurate, the FDA said. Then Binax tested it on 215 patients with pneumonia symptoms but not necessarily the strep kind. In those patients, the test was 78 percent accurate, the FDA said.
"It's not a perfect test," cautioned Gutman, who stressed that doctors should continue to use conventional laboratory tests to confirm the new rapid test.
Plus, strep isn't the only bacteria to cause pneumonia, although it is the most common bacterial culprit in outpatient doctors' offices.
Portland, Maine-based Binax said it was ready to ship the tests to doctors' offices immediately. They will cost doctors $15 to $20.