Washington ? 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 during the meeting.

“Sanofi-Aventis will be in further discussion with the FDA regarding today’s recommendations,” Dr. Doug Greene, chief medical officer at Sanofi-Aventis U.S., said in a statement.

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.