Medical Health Encyclopedia

Rapid Antigen-Detection Test for Strep Throat. A faster test called the rapid strep antigen test uses chemicals to detect the presence of bacteria in a few minutes. A positive result nearly always means that streptococcal bacteria is the cause of the infection. The test, however, fails to detect between 10 - 20% of cases, so a culture may still be necessary to catch any missed infections, particularly in children.

How Serious is Strep Throat?

The use of antibiotics has removed the threat of most complications from streptococcus infection in the throat (strep throat). However, untreated strep throat could lead to the following complications:

• Abscess in the tonsils
• Scarlet fever
• Rheumatic fever (rare in the U.S.)

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How Is Strep Throat Treated?

Strep throat infections require antibiotics. The following are generally used:

• Penicillin is usually the antibiotic of choice unless the patient is allergic. A full 10 days may be necessary. Amoxicillin, a form of penicillin, is proving to be effective when taken in a single daily dose for 10 days.
• Macrolide antibiotics. Erythromycin is known as a macrolide antibiotic and is the first choice for patients with penicillin allergies. A 10-day regimen is needed. Another macrolide, azithromycin, can be given as a single daily dose and may be effective in 5 days. It is expensive, however, and bacterial resistance to macrolides is growing, so it should not be given as a first choice.
• Cephalosporins are a potent, but expensive, group of antibiotics that are very effective in eradicating the bacteria.

Antibiotics are very commonly inappropriately prescribed for non-Strep sore throats. One study reported that estimated 6.7 million American adults visited their doctors because of sore throat between 1989 and 1999. And, 73% of them were given antibiotics. Studies indicate, however, that less than half of adults and far fewer children with even strong signs and symptoms for strep throat actually have strep infections.

Parents should be comforted that a delay in antibiotic treatment while waiting for lab results does not increase the risk that the child will develop serious long-term complications, including acute rheumatic fever. If a patient is severely ill, however, it is reasonable to begin administering antibiotics before the results are back. If the culture is negative (there is no evidence of bacteria), then the doctor should call the family to make certain they stop taking the antibiotics and discard any remaining pills.