January 02, 2006
Monday AM

When it comes to treating strep throat, older types of antibiotics are increasingly less likely to kill the germ that causes millions of sore throats, fevers and missed school days for children each year.

Yet recent studies show that as many as 90 percent of children treated for strep still get amoxicillin or penicillin rather than newer antibiotics known as cephalosporins.

One study presented at a recent scientific meeting on antimicrobials found that taking the newer drugs even for a few days is more effective against strep than the traditional 10-day course of the older antibiotics.

Pediatricians at the University of Rochester Medical Center found that 25 percent of children treated for strep with penicillin ended up back in the doctor's office within three weeks of treatment.

Children treated with amoxicillin returned 18 percent of the time. But repeat visits fell to 14 percent for youngsters who got older-generation cephalosporins, and to just 7 percent for newer types of the drugs, such as cefpodoxme and cefdinir, which can typically be given for just four or five days.

The study reviewed treatment of 11,426 children. The research was an expanded version of another study that looked at the experience of about 7,000 children.

"Most doctors are shocked to learn of the high failure rates of the older medications," said Dr. Michael Pichichero, a professor of microbiology and immunology at Rochester and co-author of the study.

"The paradigm for treating strep sore throats has been changing slowly, and endorsing the use of cephalosporins as a first-time treatment is something that needs to be seriously considered," Pichichero said.

Treatment guidelines for strep issued by the American Academy of Pediatrics, the American Heart Association and the World Health Organization all call for penicillin or amoxicillin as first drugs of choice, despite evidence that resistance to those drugs may be on the rise.

Nearly all drugs fail some of the time, Pichichero noted, and doctors often accept some risk of failure as a tradeoff for other things like convenience, cost for families and the likelihood that a less powerful drug will kill a bug as readily as a more powerful one.

On the other hand, various studies in recent years have shown that only about 15 percent to 35 percent of youngsters who come to a doctor's office with a sore throat actually have strep - most sore throats are caused by viruses, which aren't vulnerable to antibiotics.

And truth be told, strep itself isn't all that dangerous in a child with a healthy immune system. Most kids get over it without help in about a week. Traditionally, antibiotics are given because of the rare risk that the infection can get out of hand, progress to rheumatic fever and damage the heart.

More to the point in the age of day care, two working parents and the general fast pace of life, kids with strep who have been on antibiotics for 24 hours are no longer considered contagious and are allowed back in class or child care. And kids who get antibiotics also feel better within a day or two of starting them.

That largely explains the results of another recent study by researchers at Harvard Medical School and Brigham and Women's Hospital in Boston, which found that 54 percent of young patients 3 to 17 were being prescribed antibiotics for sore throat. And just half of those patients had gotten a test verifying that they had strep.

That study, which covered the years between 1995 and 2003, also found, however, that 27 percent of the children got more advanced antibiotics than penicillin, perhaps reflecting growing awareness that the newer drugs may be more appropriate.

Pichichero said while the newer short-course cephalosporins are only available in brand-name form, and are more expensive, older types of the drugs, like cephalexin, or Keflex, cost about the same as penicillin or amoxicillin and still have nearly twice the odds of eliminating the infection than penicillin.

And because the drugs don't have to be given as long, there's less risk that parents will stop giving the medicine to their children once they start feeling better, which various studies show happens anywhere from 30 percent to 70 percent of the time. Not completing the full course often leaves kids with low-level infections and cycles of on-off illness that go on for months and puts classmates at greater risk of picking up the germs, too.

Pichiechero's co-author, Dr. Janet Casey, a pediatrician at the University of Rochester Medical Center, said she doesn't think penicillin should be abandoned, but "in my own practice, given the results of our analysis, I find it very difficult not to prescribe cephalosporin drugs to my patients."

Pichichero said the problem with penicillin might not be that the strep germs themselves are resistant to it, but that some of the other types of bacteria that have staked out territory in a child's throat may have become indifferent to it after repeated exposure.

He noted that at least four types of bacteria that he calls "co-pathogens" to strep are known to become more dominant in the throat of someone who has frequently been treated with penicillin, and those germs may actually serve to shield strep from the antibiotic.

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