About 600 people who picked up mail and packages at a postal processing facility where anthrax was found should take antibiotics, state health officials said Saturday. 

The recommendation applies mainly to workers from several hundred firms who pick up or drop off mail from nonpublic areas at the Hamilton Township facility, the source of three anthrax-tainted letters sent to New York and Washington.

At least five New Jersey postal workers have confirmed or suspected cases of the disease. A Trenton firefighter also was hospitalized Saturday for a possible case of inhalation anthrax.

Also Saturday, officials closed the Princeton post office after a single anthrax spore was found in a colony of several types of bacteria on a mail bin, health department spokesman Tom Slater said.

The 60 to 70 workers there do not need antibiotics because the level of contamination was minuscule, said state Health Commissioner George DiFerdinando. But he said workers will get help in obtaining antibiotics if they choose to be treated.

``Since we consider the single colony to be an insignificant amount, we don't believe the benefit of treating them at this time is worth the risk of side effects to those people,'' he said.

The health commissioner said test results from a third postal facility, the West Trenton post office in Ewing, were negative. A decision on reopening that facility would likely be made Sunday, he said.

Twenty samples that came back negative were initially reported to have come from the West Trenton post office but actually came from the Hamilton facility, he said.

Health officials stressed that people who visited public areas of the Hamilton post office — where stamps are bought, mailboxes located and mail is weighed and stamped — do not need antibiotics. Those areas have tested negative.

A Trenton firefighter was hospitalized Saturday for a possible case of inhalation anthrax, Battalion Chief Douglas Pierson said.

George Gennaoui, a spokesman for Capital Health System-Fuld campus, said the firefighter came in for testing because he picked up mail for the department. Swab tests came back positive, and a chest X-ray caused concern among doctors.

The firefighter's condition is stable, and he's being treated with antibiotics, Gennaoui said. Test samples were sent to the state health department Saturday, and results won't be in for at least two days.

The health department said a second Hamilton postal worker whose case has been upgraded to a ``suspected'' case of inhalation anthrax has been released from the hospital. The woman, who remains on antibiotics, first showed symptoms Oct. 15, Otterbourg said.

The first case at the Hamilton office was a woman with inhaled anthrax whose condition has improved, according to health officials. She remains hospitalized.

Three other New Jersey postal workers are being treated for confirmed or suspected cases of the skin form of the disease. Also, five workers at the Hamilton or West Trenton facilities have tested positive for exposure to anthrax.

DiFerdinando said he was not sure how the mail bin in Princeton became contaminated. The bin could have been used in Hamilton before it was taken to Princeton, he said. Or there may be separate contamination in the Princeton facility, located in West Windsor.

New Jersey's U.S. senators, Robert Torricelli and Jon Corzine, urged postal officials this week to test and provide antibiotics for all workers in the 46 post offices that feed into the Hamilton processing center.

The Postal Service announced Friday that mail facilities across the country will be tested randomly for anthrax.