AHA Updates Advice on Strep Throat, Preventing Rheumatic Fever

March 06, 2009

From Heartwire — a professional news service of WebMD

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March 6, 2009 — New advice on preventing rheumatic fever by the appropriate diagnosis and treatment of acute streptococcal pharyngitis has been published in a scientific statement from the American Heart Association (AHA) [1].

Lead author Dr Michael A Gerber (Cincinnati Children's Hospital, OH) told heartwire this is an update to a statement issued in 1995 by the same committee and that there are a few key differences between the two, namely in certain issues regarding the diagnosis of strep throat and serologic testing for antistreptococcal antibodies and in some of the treatment recommendations for primary prevention of rheumatic fever. The statement was published online February 26, 2009, in Circulation.

In an accompanying editorial [2], Dr Alan L Bisno (University of Miami, FL) says: "The task facing the primary-care physician is to identify and appropriately treat the minority of sore-throat patients suffering from strep throat and to avoid unnecessary and potentially deleterious treatment for the remainder, who likely suffer from self-limited viral pharyngitis. The most appropriate methods to accomplish this task are, in my opinion, well enunciated in the [new] AHA statement."

Rheumatic Fever Rare in Developed World

Gerber — a pediatrician who specializes in infectious diseases — serves on the AHA Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, which has issued the statement. He said the new guidance would primarily be of interest to primary-care physicians, rheumatologists, pediatricians, and cardiologists.

Rheumatic heart disease is the most important sequela of acute rheumatic fever, which is caused by group A streptococci (GAS) and usually presents in childhood, affecting five- to 15-year-olds — although it can strike people up to the age of 30. In 20% to 30% of cases, there is no cardiac involvement, but people often contract rheumatic fever more than once, and the damage is cumulative.

Gerber explained that in developing areas of the world, acute rheumatic fever and rheumatic heart disease are estimated to affect nearly 20 million people and are the leading cause of cardiovascular death during the first five decades of life.

However, in the developed world, the incidence of acute rheumatic fever has decreased dramatically. "If our whole hospital has four or five cases a year, that would be a lot," said Gerber, adding that the usual number of cases his institution encounters annually is one or two. But there have been occasional "focal outbreaks" of the disease, he noted, such as the one that occurred in Salt Lake City in the 1980s.

Culture Backup Needed for Children Suspected of Having Strep Throat

The prevention of initial attacks of rheumatic fever (primary prevention) requires accurate recognition and proper antibiotic treatment of strep throat, which is best accomplished by combining clinical judgment with diagnostic test results, say the experts.

"Although this is not new, one of the most important parts of the statement is that you really cannot accurately diagnose strep throat on the basis of clinical findings; you still need some form of microbiological confirmation," Gerber told heartwire .

"If you treated everybody with antibiotics based on a clinical assessment, the predictive value would be no better than 70%, so 30% of people would be getting antibiotics unnecessarily, contributing to the huge problem of bacterial resistance," he notes.

Gerber said the so-called "rapid strep test" has now replaced throat cultures in the US, and the new statement has some particular advice on this. "It's unusual to get a false-positive rapid strep test," says Gerber, "so if you do this test and it's positive, you can be pretty confident the person has strep throat."

But false negatives "are not uncommon," he says, and the new advice if the rapid strep test is negative differs depending upon the age of the patient.

In a child, a negative rapid stress test "is now recommended to be confirmed by a throat culture," he says. But in adults, this is not necessary for two reasons. First, adults are much less likely to have strep throat, and second, initial attacks of rheumatic fever are rare in adults.

Bisno points out in his editorial that the statement does not indicate the age at which culture backup can be abandoned, however.

Issues Surrounding Serologic Testing

Other new information in the statement includes a discussion of some of the problems surrounding serologic testing for antistreptococcal antibodies. "This is performed not so much in making a diagnosis of strep throat but to confirm a previous GAS infection, ie, that someone who is suspected of having rheumatic fever or poststreptococcal glomerular nephritis has a serologic response, because by that time, their throat culture would be negative," Gerber explained.

The most commonly used assays for serologic testing are now automated tests such as antistreptolysin O (ASO) and antideoxyribonuclease B (ADB), which are much quicker than the older, labor-intensive neutralization assays, Gerber says. "However, it is important for physicians to understand that these newer tests haven't been standardized and are not established as being reproducible, so the results are very hard to interpret relative to the standard [neutralization assays] done in the past," he points out.

Also, a commercially available slide agglutination test, known as Streptozyme (Wampole Laboratories, Stamford, CT) "has always been regarded by the World Health Organization as not accurate," says Gerber, but "physicians continue to use it because it's inexpensive and easy to perform." But this "should not be used as a test for evidence of a preceding GAS infection," the statement asserts.

Changes to Treatment Recommendations

Finally, the new statement contains updated information on recommended antibiotic treatment schedules for strep throat. The treatment of choice is oral or intramuscular penicillin, but Gerber said one of the main changes is the acknowledgment that once-a-day amoxicillin is a suitable alternative, particularly for young children who cannot take pills and who can instead take amoxicillin suspension, which also has the advantage of being more palatable than penicillin, he noted.

For those who are allergic to penicillin, apart from severe type 1 allergic reactions, "the new recommendations deemphasize the use of macrolides such as azithromycin," said Gerber, because there is increasing resistance of GAS to this group of antibiotics "and they are not as well tolerated, often provoking gastrointestinal symptoms." So the recommendation now is to start with a narrow-spectrum cephalosporin or clindamycin, he says. For those with severe type 1 allergies to penicillin, "clindamycin should be the first choice," he says, because there is a 10% crossover [for allergy] with narrow-spectrum cephalosporins.

Finally, individuals who have had an attack of rheumatic fever are at very high risk of developing recurrences after subsequent GAS pharyngitis and need continuous antimicrobial prophylaxis to prevent such recurrences (secondary prevention), the AHA statement notes.

The recommended duration of secondary prophylaxis and agent depends on a variety of factors that are outlined and have not changed significantly since the 1995 statement.

Dr. Gerber has disclosed no relevant financial relationships. Coauthor Dr. Stanford Shulman (Children's Memorial Hospital—Northwestern University, Chicago, IL)has received a research grant from and being a consultant on the advisory board of Quidel Corp. A complete list of disclosures for the other authors is available in the original article.

Editorialist Dr. Bisno has disclosed consultant relationships with Advancis Pharma (now Middlebrook), Cornerstone Biopharma, Merck, Schering-Plough, and Targanta Therapeutics.

  1. Gerber M, Baltimore R, Eaton C, et al. Prevention of rheumatic fever and diagnosis and treatment of acute streptococcal pharyngitis. A scientific statement from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee of the Council on Cardiovascular Disease in the Young, the Interdisciplinary Council on Functional Genomics and Translational Biology, and the Interdisciplinary Council on Quality of Care and Outcomes Research. Circulation. 2009; DOI: 10.1161/CIRCULATIONAHA.109.191959. Available at: http://circ.ahajournals.org

  2. isno AL. Prevention of rheumatic fever, today and tomorrow. Circulation. 2009.

The complete contents of Heartwire , a professional news service of WebMD, can be found at www.theheart.org, a Web site for cardiovascular healthcare professionals.

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