However, officials with the Centers for Disease Control and Prevention say the release is not a danger to the general public because there's no evidence suggesting the germ travelled off the research centre campus.
The germ, called Burkholderia pseudomallei, is found in tropical climates — particularly Southeast Asia and northern Australia. People and animals generally get it through direct contact with contaminated water and soil. It is not believed to spread from person to person.
Federal officials believe that in November, the bacteria spread from a lab to other areas of the Tulane National Primate Research Center in Covington. Eight monkeys kept outside the lab were later found to be infected.
A two-month investigation found some lab workers were lax about tying closed and taking off outer garments. When they finished their work in the lab, Tulane workers commonly kept on the scrubs and shoes they wore underneath those outer garments, CDC investigators found.
Officials believe the bacteria hitched a ride on those scrubs and shoes when workers walked to other areas. "That's what we think is the most likely cause" of the release, said the CDC's Robbin Weyant.
CDC officials presented the findings of their investigation to Louisiana officials during a meeting Friday morning.
In a statement Friday, Tulane officials said "we apologize for any anxiety, discomfort or inconvenience this incident has caused." Tulane has made corrective changes, including mandating a "shower-out" process that requires employees to shed any clothing worn in the lab before going to other parts of the campus. All clothing and other lab garments will be disposed of as bio-hazardous waste, a spokesman said.
There's also been more training about how to properly wear protective outer garments, and Tulane has turned to a national expert for further guidance, officials said.
The Tulane spokesman, Michael Strecker, declined to say whether any staff were fired or suspended.
Most people infected with these bacteria do not get sick. But some come down with melioidosis — also known as Whitmore's disease — which can sicken humans or animals and in some cases prove fatal.
The government classifies Burkholderia pseudomallei as a germ or toxin that could pose a severe threat to the public health. The Tulane research centre is about 50 years old, but has been working with such germs since about 2008, CDC officials said.
The research centre has 300 employees.
Tulane lab staff was working with the germ to develop a vaccine, in experiments involving mice.
Animal care workers were also in and out of the lab and are a possible route for the bacteria's spread, CDC officials said.
The CDC works closely with the U.S. Department of Agriculture to monitor research facilities that use select agents in experiments with animals.
The CDC is presenting its findings to the agency, which will consider the possibility of fines or penalties, said Weyant, the director of CDC's Division of Select Agents and Toxins.
No serious violations of this sort have been detected at the Tulane centre before, CDC officials said. Investigators were able to document the lax clothing practices through videotape, Weyant said.
A Department of Agriculture worker involved in the Tulane investigation has been found to have low levels of antibodies to the bacteria, but officials have concluded that likely came from exposure to the germ during a past overseas trip. A Tulane employee this week was found to have antibodies during an initial test. But additional tests will be needed to confirm that the person has been infected with Burkholderia pseudomallei, and that it came from a recent exposure at the lab, CDC spokesman Jason McDonald said.