To Dose Or Not To Dose?

THE introduction of antibiotics during World War II represented perhaps the greatest medical advance since the discovery that drinking water should not be taken from a dirty well. So what better to sic these miracle drugs on than middle-ear infections, that scourge of childhood? Otitis media accounts for more visits to pediatricians than any other illness (24.4 million in 1990, up almost 150 percent since 1975). Sure enough, the usual treatment for otitis media these days is a 10-day course of the antibiotic amoxicillin. Yet it remains such a confusing illness that doctors continue to argue about how to treat it, and even about whether antibiotics make any difference.

Otitis media may be a consequence of children's anatomy (diagram). Most of the time, the eustachian tube allows air to flow into the middle ear. In infants and toddlers the tube's geometry allows it to be blocked by, say, a cold. Bacteria in the nose can then ride a river of mucus upward to infect the middle ear. The outward symptoms of pain and fever mark this as acute otitis media (AOM).

In 1994 a group of researchers at George Washington University and the University of Minnesota looked into just how good antibiotics are at curing AOM. Using a statistical technique called metaanalysis, they combined the results of 33 earlier studies evaluating the efficacy of various antibiotics. It turned out that the drugs have only about a 14 percent advantage over the body's own immune system. in other words, for every child who needs antibiotics to clear the infection, six can recover without them.

How can this be? Cells lining the middle ear produce proteins called immunoglobulins that interfere with the bacteria's ability to infect; enzymes and killer cells destroy bacteria outright. "You're overtreating six patients to capture the seventh who's going to get m trouble," says Dr. Charles Bluestone, the director of pediatric otolaryngology at Children's Hospital in Pittsburgh. "The problem is, we don't know which is which."

So doctors treat them all. That avoids complications like meningitis, an infection of the lining of the brain, and mastoiditis, an infection of the bony space next to the middle ear. Both virtually vanished with the use of antimicrobials. Today all the common AOM bugs are becoming more and more resistant, but few doctors--and fewer parents--will leave a child's ear infection up to her immune system.

The confusion extends to otitis media with effusion (OME), a painless condition in which the eustachian tubes are blocked and the middle ear fills up with fluid. It almost inevitably follows AOM, and can result in mild hearing loss. In 90 percent of cases hearing is back to normal in three months or less--antibiotics neither help nor hinder. Whether that loss affects a child's language development is hotly debated, as are possible complications of surgery to implant drainage tubes.

At least OME has government guidelines for treatment, like waiting three months before surgery. No such guidance exists for AOM. "We're still at a point where the risks of not treating outweigh the risks of treating," says Jack Paradise, a pediatrician at the University of Pittsburgh. "That's a delicate balance that could change." Meanwhile, parents watch and wait.

The shape and position of their eustachian tubes make infants vulnerable to ear infections. Adult tubes are narrower and at a steeper angle, so they drain better.

Acute otitis media: The middle ear fills with gunk; it may get better on its own, but doctors generally prescribe the antibiotic amoxicillian.

Otitis media with effusion: Clear fluid fills the ear and can impair hearing. After three months, doctors may implant tubes to drain the blockage.