Washington - Federal officials found more than just long-forgotten smallpox samples recently in a storage room on the National Institutes for Health campus in Bethesda, Maryland. The discovery included 12 boxes and 327 vials holding an array of pathogens, including the virus behind the tropical disease dengue and the bacteria that can cause spotted fever, according to the Food and Drug Administration, which oversees the lab in question.

"The fact that these materials were not discovered until now is unacceptable," Karen Midthun, director of the FDA's Center for Biologics Evaluation and Research (CBER), told reporters Wednesday. "We take this matter very seriously, and we're working to ensure that this doesn't happen again."

The disclosure came hours after Thomas Frieden, director of the Centers for Disease Control and Prevention, testified on Capitol Hill that researchers at the agency mishandled live anthrax and other deadly pathogens in a string of mishaps in recent years. "We missed a critical pattern," he told lawmakers. "And the pattern is an insufficient culture of safety."

Both the smallpox discovery and the previously undisclosed safety lapses at the CDC have sowed doubt about how the nation's premier public health and research institutions are safeguarding some of the most lethal organisms on Earth.

The vials of smallpox, a scourge that was eradicated decades ago after killing hundreds of millions of people in the 20th century alone, remain the most disturbing find this month inside the third-floor cold storage room in Building 29A. Those samples were flown to the CDC in Atlanta, and at least two have shown growth in tissue cultures, meaning they are viable, or alive.

On Wednesday, the FDA said that along with dengue and rickettsia, the bacteria that can cause spotted fever, the additional vials contained such microbes such as influenza and Q fever, a bacteria that can cause complications with the heart, lungs and liver. The samples were in well-packed, heat-sealed vials and showed no signs of leakage. No evidence exists that anyone has been exposed to the pathogens, the agency said.

"The reasons why these samples went unnoticed for this long is something that we're actively trying to understand," said Peter Marks, CBER's deputy director, adding that the boxes were in a seldom-accessed storage area.

The FDA said the collection "was most likely assembled between 1946 and 1964 when standards for work with and storage of biological specimens were very different from those used today."

The smallpox vials were labeled with a date-Feb. 10, 1954-Frieden said last week, adding that it appeared that whoever left them at NIH "didn't do so out of malice."

The FDA said Wednesday that it is reviewing its safety protocols and digging through all other similar storage rooms, at its headquarters and nationwide, to make sure no more vials are tucked away in forgotten corners.

Frieden was summoned to testify before a House Energy and Commerce subcommittee about last month's incident in which more than 80 CDC employees may have been exposed to live anthrax when samples were transferred from one lab to others. The agency said last week that there had been at least four other incidents in the past decade in which deadly pathogens were mishandled, including one in which employees mistakenly sent a sample contaminated with the deadly H5N1 influenza virus to government researchers in Georgia. None of those incidents had been previously disclosed.

Subcommittee Chairman Tim Murphy, R-Pa., said government watchdogs have documented numerous systemic safety lapses over the years. He called the most recent incident "sloppy" and "inexcusable," saying the agency's labs are supposed to be "the gold standard" for the U.S. health system.

Rep. Fred Upton, R-Mich., noting that Frieden had made similar promises to improve safety and accountability in the wake of previous incidents, asked, "Why should we believe you this time that things are going to be different?"

Although Frieden pointed out that no one had been hurt and that all pathogens were killed in the incidents, he said that was no excuse and vowed to improve the agency's overall safety culture, as well as put in place stronger oversight measures. He said workers must be encouraged to report any incidents that happen and "apply the same rigor" to safety as to disease prevention and research.

In response to the recent lapses, the CDC has closed two labs-its bioterrorism rapid response lab and an influenza lab that deals with highly pathogenic flu viruses. It also has halted shipment of biologic materials from 22 of its highest-security labs until a safety review is complete. Priority for reopening will go to those doing work related to immediate patient care and public health, Frieden said. The CDC's work on this year's upcoming flu vaccine is finished and won't be affected, agency spokesman Tom Skinner said. But work on vaccines for countries in the Southern Hemisphere, where flu season arrives later, is likely to be affected by the moratorium, he said.

At several points during the hearing, Murphy held up a Ziploc bag containing petri dishes with photos of anthrax bacteria glued to them and asked why scientists would be using plastic bags to transport dangerous pathogens. Murphy was referring to an investigation by the Agriculture Department's animal and plant health inspection service, which found that, among other safety failures, samples of the bacteria were stored in unlocked refrigerators in unrestricted hallways and that dangerous material was transferred in Ziploc bags.

Frieden said researchers working with those samples thought the anthrax had been inactivated, but scientists at the CDC bioterrorism lab had not killed the bacteria before transferring samples to other labs.

Witnesses also described the lack of coordination and oversight at laboratories inside and outside the federal government that conduct research on microbes that could be used as bioterrorism agents. Nancy Kingsbury, a managing director of the Government Accountability Office, told the committee that since the 2001 anthrax attacks that killed five people, her agency has repeatedly warned about problems that could arise from the proliferation of biosafety labs. Nearly 1,500 registered laboratories in the United States conduct this kind of research, according to the GAO.

But no single agency sets national standards or provides oversight, she said. No one, she said, has been able to address key questions: "How many do we really need? For what purpose? Against what threat?"

Richard Ebright, a chemical biology professor at Rutgers University who conducts biosafety research, said multiple safety lapses at CDC labs over the years have been documented by government watchdogs, including the inspector general's office at the Department of Health and Human Services and the GAO.

Last month's event was "not an isolated event," Ebright said. It occurred, he said, because "hubris is a fundamental part of the problem," noting that researchers often think they can proceed without restrictions or management.