WASHINGTON (AP) - The number of Americans taking anthrax-fighting antibiotics at the government's urging neared 10,000, while inspectors found more of the deadly bacterium in a Senate office building. The postal service prepared to issue masks and gloves for its 800,000 employees and was testing ways to sterilize the nation's mail.

Federal health officials announced that a deal had been struck with the Bayer Corp. to buy 100 million tablets of Cipro, the antibiotic that more and more Americans are popping to ward off the risk of anthrax disease. Health and Human Services Secretary Tommy Thompson said the government would purchase Cipro for its drug stockpiles for 95 cents a pill.

Centers for Disease Control and Prevention spokeswoman Kay Golan said the number of people the government now has taking Cipro or other antibiotics against anthrax was "approaching 10,000," although she said a precise number was not known. Uncounted others have obtained the antibiotic from private physicians.

Health officials pleaded with people to not self-medicate with Cipro purchased over the Internet because the drug can have side effects for some people.

Since the anthrax-by-mail crisis began, there have been six cases of inhaled anthrax, the most serious form of the disease. Two postal workers in Washington and a tabloid photo editor in Florida have died.

There are 15 patients in the Washington area with symptoms suggestive of anthrax and all may linked to a letter sent to Senate Majority Leader Tom Daschle and handled in mail facilities from Trenton, N.J., to Capitol Hill. However, investigators have not ruled out the possibility there was other anthrax-laced mail that has not been found.

Six cases of skin anthrax, a less dangerous form of the disease, have been diagnosed and there is a suspected case reported at the New York Post. These mostly are connected to mail sent to TV networks or to newspapers.

Officials said a female employee of an electronic news organization was being treated for possible inhalation anthrax was outside Daschle's office the day the tainted letter was received - the first time they have said a possible case of inhalation anthrax may have come from exposure inside the Capitol complex.

Surgeon General David Satcher admitted "we were wrong" not to respond more aggressively to tainted mail in the nation's capital.

Postmaster General John F. Powers warned that the postal service could not guarantee the safety of the mails and that people should wash their hands after handling a letter or package.

Postal service vice president Deborah Willhite said postal workers in Washington, New York and Trenton, N.J., all sites where anthrax-tainted mail was handled, have been offered masks and gloves of a type recommended by the CDC. The protective coverings will be offered to all 800,000 postal workers by the end of the week on an "optional, not mandatory" basis, said Willhite.

She also said the postal service was experimenting with ways to cleanse the nation's mail. "Tractor trailers of mail are to be sanitized," said Willhite in tests to determine the best way to kill any dangerous organisms contained in letters or packages.

Police said that anthrax spores were found on a first-floor freight elevator bank in the Hart Senate Office Building, the same building where an anthrax-tainted letter addressed to Daschle was opened.

Capitol Police Lt. Dan Nichols said investigators were trying to determine how the anthrax got to the freight elevator bank. The Hart building and other congressional office buildings have been closed since Oct. 17.

Sen. Bill Frist, R-Tenn., a surgeon before becoming a senator, predicted in an Associated Press interview, that "there will be more illness" from anthrax.

He also said the sophistication required to process the anthrax spores used in the postal attacks suggested that "more than a casual scientist is involved."

CDC Director Dr. Jeffrey Koplan made a similar point in a television interview. "I think that whoever did this is displaying some level of sophistication in everything from microbiology to psychology and sociology and a range of other issues," Koplan said on PBS' "The NewsHour With Jim Lehrer."

Although he said there was no direct evidence linking the Sept. 11 airliner attacks with the postal anthrax, President Bush said, "Anybody who puts poison in mail is a terrorist."

Scientists at several medical labs have spent days analyzing the deadly bacteria, but Koplan said it still was unclear whether the mailed anthrax spores, which have caused illness in New York, Washington, Florida and New Jersey, all came from the same place.

However, a story in Thursday editions of The Washington Post quoted government sources as saying the anthrax that contaminated Daschle's office may have been made in America.

The story said the anthrax was treated with a chemical additive made only in the United States, the former Soviet Union and Iraq. It quoted an unnamed source as saying that "the totality of the evidence in hand" suggests it was unlikely to have come from the former Soviet Union or Iraq.

Copyright 2001 The Associated Press. All rights reserved.