WASHINGTON (AP) – Benefits of an antibiotic linked to rare reports of severe liver problems, including several deaths, outweigh its risks in treating pneumonia but not less serious bacterial infections like bronchitis and sinusitis, federal health advisers said Friday.

The nonbinding recommendations raise the prospect the Food and Drug Administration could modify its approval of the Sanofi-Aventis SA drug, called Ketek, to exclude the treatment of the two lesser infections, which often clear up without drug treatment.

The FDA convened a two-day meeting of outside experts to discuss Ketek in light of concerns about its safety. An agency review found 13 reports of liver failure in patients treated with the drug through September. Reports of blurry vision also have been a concern. Doctors have prescribed the antibiotic more than 5.6 million times in the United States since the FDA approved it in 2004.

On Friday, the FDA panelists voted 16-3 to say Ketek’s benefits outweigh its risks in treating pneumonia. In 17-2 votes, the outside advisers said that wasn’t the case for bronchitis and sinusitis, which are less serious infections and often spontaneously resolve on their own.

Dr. John Jenkins, director of the FDA’s office of new drugs, declined to say what action the agency would take. The FDA isn’t bound to follow the advice of its outside experts, but usually does.

“We will be assessing the advice we received from the committee and discussing that very shortly,” Jenkins said.

The panel also recommended Sanofi-Aventis develop a medication guide to be given to patients, a move backed by the company.

Dr. John Edwards, of Harbor-UCLA Medical Center in Torrance, Calif., and the panel’s acting chairman, called the two-day meeting particularly challenging, since it came amid concern that companies have diminishing interest in developing new antibiotics and increased interest in safety issues linked to the drugs.

Many experts fear overuse of antibiotics is hastening the increasing resistance of many bacteria to older drugs, making the development of novel treatments critical. Some panelists suggested reserving Ketek for second-line use in treating pneumonia.

The label of the drug was changed in June to add a bold-type warning about the rare reports of liver failure and severe injury, some of them fatal. A majority of panel members said that cautionary language should be strengthened and placed in a so-called “black box” to warn doctors and patients of some of the risks associated with the drug.

The FDA’s handling of Ketek remains under investigation by a Senate committee. Sen. Charles Grassley, R-Iowa, said this week the FDA intentionally withheld information from FDA advisers when they met in 2003 to consider recommending approval of the drug. FDA officials said they would comment after reviewing his allegations, contained in a 20-page letter sent to the agency.

Sanofi-Aventis said the risks associated with the drug, also known as telithromycin, appear to be comparable to those of other similar drugs and that it represents an important option in treating respiratory tract infections.