CHICAGO (AP) - New U.S. research suggests antibiotics offer little benefit in treating most acute sinus infections in children, despite guidelines that recommend their use when symptoms last at least 10 days.

Given growing concern that the overuse of antibiotics creates drug-resistent germs, the authors say their findings indicate such guidelines should be revised.

Acute sinusitis is an inflammation of membranes lining the facial sinuses - air spaces among bones that surround the nose and eyes. It affects perhaps 20 million U.S. adults and children yearly and is among the most common childhood ailments for which antibiotics are routinely prescribed, said lead researcher Dr. Jane Garbutt of Washington University School of Medicine.

Sinusitis can be caused by viruses or, less commonly, bacteria; the only ``bugs'' antibiotics work against are bacteria. Serious complications such as meningitis can occur with either form but are rare.

The ailment is difficult to diagnose in children because their symptoms often are simply those of a lingering cold and cough without the facial pain and fever typically seen in adults.

The study, which involved 161 American children with up to four weeks of symptoms and diagnosed with acute sinusitis, appears in April's edition of Pediatrics.

The youngsters, aged 8 on average, were given one of two common penicillin-type amoxicillin drugs or dummy pills for two weeks. By the 14th day of treatment, about 80 percent of patients in each of three groups showed similar improvement.

``Antimicrobial treatment offered no benefit in overall symptom resolution, duration of symptoms, recovery to usual functional status, days missed from school or child care, or relapse and recurrence of sinus symptoms,'' the authors wrote.

The results echo research on adults and follow recommendations issued in March by the American College of Physicians-American Society of Internal Medicine. That group says over-the-counter remedies rather than antibiotics generally are the best treatment for most sinus infections in adults.

Existing guidelines for children stem from a 1998 consensus statement by specialists at the U.S. Centers for Disease Control and Prevention and elsewhere. They note that sinus infections caused by viruses are up to 200 times more common than those caused by bacteria.

Nevertheless, the guidelines recommend treatment with amoxicillin or similar drugs for children with upper respiratory symptoms such as nasal discharge of any color and cough who don't improve after 10 to 14 days.

It was once thought that greenish mucous signaled a bacterial infection but doctors now believe it is simply a sign of inflammation, Garbutt said.

She said the findings suggest that doctors wait until symptoms have lasted at least three weeks before prescribing antibiotics.

The American Academy of Pediatrics follows the 1998 recommendations but its Committee on Quality Improvement is developing its own guidelines that should be completed in the next few months, a spokeswoman said.

Copyright 2001 The Associated Press. All rights reserved.