HARTFORD, Conn. When September rolls around, parents know it won't be long before schoolchildren start bringing home projects, report cards and group A streptococcal (GAS) pharyngitis.
Not every red throat heralds a GAS infection. In fact, most cases of acute pharyngitis are not caused by Streptococcus pyogenes but by a virus, said Michael Gerber, MD, director of the division of infectious diseases, Connecticut Children's Medical Center here.
Certain clinical and epidemiological findings suggest a diagnosis of GAS pharyngitis. The child is usually between 5 and 16 years of age, the season is usually winter or early spring and the child often has had contact with someone with acute GAS pharyngitis.
"GAS pharyngitis is not common in day care settings, but it does occur," Gerber said. "Physicians need to be aware of it, but they do not need the same index of suspicion as in school-aged children. We don't exactly know why. There have been some outbreaks in day care, but in these children it does not usually present as acute pharyngitis but a nasopharyngeal infection. It is not a typical strep throat."
Regardless of when pharyngitis occurs, viruses are the most common cause.
"Even at the appropriate age, most children don't have GAS," Gerber said. "They don't benefit from antibiotics, so it is important to make an accurate diagnosis."
A culture or a rapid strep test is the only way to definitively distinguish a GAS infection from a viral one, but these tests may also detect streptococci in chronic carriers, who are generally not treated. The carrier state is more difficult to eradicate than an acute infection because in the carrier state, the bacteria do not respond well to penicillin.
"Carriers do not need to be treated in most cases. They are not at risk for rheumatic fever, glomerulonephritis or other complications. There is little evidence that they pass GAS along to their contacts. It is a benign state for carriers and the people around them," Gerber said.
To avoid misdiagnosing an acute GAS infection in a carrier, Gerber suggested performing cultures or rapid strep tests only on those patients who are likely to have GAS pharyngitis. Although GAS cannot be diagnosed based solely on clinical findings, some symptoms tend to be associated with GAS infections and others are more common in viral infections.
"If a child has repeated episodes of GAS pharyngitis, this needs to be distinguished from the carrier state," Gerber said. "It is more common to have a sore throat superimposed on a carrier state with streptococci not being the cause of the pharyngitis."
The child should be tested between episodes to determine whether the infection is indeed recurrent GAS. If a between-episode test is positive for GAS, if the clinical symptoms suggest a viral cause, if the episodes occur during seasons when GAS is unlikely, and if the child does not respond clinically to antibiotics, the child is probably a carrier and the infection has another cause. No treatment is necessary.
If, however, the test between episodes is negative, symptoms are consistent with GAS pharyngitis and the child responds clinically to antibiotics, the episodes are probably recurrent GAS. Recurrent GAS infections represent a situation where antibiotic therapy is indicated.
"In situations where there is recurrent GAS infection or where it appears to be 'ping-ponging' through a family, culture everybody in the family and treat everyone who is infected or a carrier," Gerber said. Despite theories that family pets act as carriers, "don't treat the pets. Pets don't play a role."
Although some providers recommend daily doses of penicillin for children with recurrent GAS pharyngitis, "that has not been shown to be effective," Gerber said. "I would recommend it before a tonsillectomy, but there is no scientific evidence that it works, only anecdotal evidence."
There is also no evidence that GAS is becoming resistant to penicillin.
"Penicillin resistance is becoming a major problem with Streptococcus pneumoniae." Gerber said. "No S. pyogenes strains have been found to be penicillin resistant. That is often confused. Penicillin resistance has never been a problem with GAS."
Using penicillin improperly to treat misdiagnosed viral infections or to treat patients with acute viral pharyngitis who are chronic streptococcal carriers may contribute to the myth of penicillin resistance of this organism.
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