Latest update claimed that CDC scientists put anthrax into a chemical bath to inactivate it for 24 hours, but after only ten minutes took out a sample for plating and culturing to determine if viable spores remained. They failed to plate the anthrax that was transferred, after 24 hours in a chemical bath. And it was the spores that were in the bath for 24 hours that were shipped to other labs.
What researchers are trying to find out is whether that was long enough to kill the anthrax, Dr Paul Meechan, director of the CDC’s environmental health and safety compliance office, told Reuters in a telephone interview.
“We don’t know that, but we’re doing experiments to prove it,” said Meechan. The CDC first disclosed the incident to Reuters a week ago.
An independent laboratory is running the same set of experiments to see if they get the same answers, which would add to the validity of the findings.
Meechan said workers in the bioterror lab were testing a new protocol for inactivating anthrax before sending the bacteria for experiments in two lower-security CDC labs.
The protocol they were following had been used by researchers at the CDC to inactivate other bacteria, but not on anthrax. It called for placing anthrax into a bath of acid for 10 minutes, removing some, putting it on a nutrient-rich plate and placing it in an incubator.
After 24 hours, the researchers checked to see if any colonies of anthrax had grown. None had, so the team took the anthrax that had been soaking in acid for 24 hours, put it on slides and sent it for testing in two other CDC labs.
1. Why did it take 10 days for this piece of information to be reported?
2. Why is CDC only now doing the allegedly appropriate experiment to determine if there even was an exposure to live anthrax, more than 2 weeks after the mistake was discovered?
3. If scientists truly kept the anthrax spores in a bath for 24 hours, then they should have plated those spores to check for inactivation. CDC says it is only now doing the experiment to see if 24 hours in the bath inactivates anthrax spores. Really? Only now you are doing the experiment that needed to be done (according to your own protocols) before any anthrax was sent elsewhere?
4. Anthrax, when healthy, can go through enough doublings to form a visible colony on an agar plate in 18-24 hours. After a bath in a harsh chemical, one should not assume they grow as fast. Even a small growth delay could require more time for visible growth on agar. Even 48 hours should not be enough time to rule out the presence of viable, possibly mutated and slower-growing spores.
5. Did researchers start with spores or vegetative forms of anthrax? Vegetative forms are easily killed–but may convert to spores when placed in harsh conditions. The spores can survive whatever method kills only the vegetative form. Was there vegetative cell to spore conversion?
6. To perform a valid experiment, you test one parameter of the experiment. However, media reports claim that CDC scientists were testing a new method to detect anthrax. To do so they were using anthrax that was killed by a new method. When you have two variables (new methods) in this type of experiment, you need extra experimental arms to control for the presence of two variables. There have been no reports that the experiment took this into account. Therefore the CDC experiment for which the anthrax was prepared was likely an example of junk science, i.e., could not produce a valid answer to the question posed no matter what result was obtained.
7. Why, a week after the problem was discovered, had only 2/3 of potentially exposed individuals been seen by occupational health and treated using CDC-established post-exposure prophylaxis protocols?
8. Here are CDC’s recommendation for handling and proving the inactivation of anthrax spores (which were not followed) that were issued after a similar incident exposed lab workers to live anthrax at Oakland Children’s Hospital in June 2004:
Inactivated suspensions of B. anthracis should be cultured both at the preparing laboratory before shipment and at the research laboratory several days before use to ensure sterility. Sensitivity of sterility testing might be enhanced by increasing the inoculum size and incubation time, and by inoculating in multiple media, including both solid and broth media. Such procedures would increase the probability of detecting even a small number of viable B. anthracis spores. CHORI staff members did not perform sterility testing on the suspension received in March 2004.
Because inhalation of viable B. anthracis spores can result in fatal infection, CDC recommends that laboratory personnel who routinely perform activities with clinical materials and diagnostic quantities of infectious cultures implement BSL-2 practices (7). These practices include use of appropriate PPE (e.g., gloves, gowns, or laboratory coats) and a BSC for procedures with the potential to expel infectious aerosols (e.g., centrifuging or ejection of pipette tips). Face protection (e.g., goggles, face shield, or splatter guard) should be used against anticipated splashes or sprays when potentially infectious materials require handling outside of the BSC. In the incidents described in this report, because CHORI staff members believed they were working with nonviable organisms, they did not fully implement BSL-2 practices until after the deaths in the second group of mice.
Research laboratory workers should assume that all inactivated B. anthracis suspension materials are infectious until inactivation is adequately confirmed. BSL-2 procedures should be applied to all suspension manipulations performed before confirming sterility. After sterility is confirmed, laboratory personnel should continue to use BSL-2 procedures while performing activities with a high potential for expelling aerosolized spores.
The Advisory Committee on Immunization Practices recommends routine anthrax vaccination of persons who work with production quantities or concentrations ofB. anthracis cultures or perform other activities with a high potential for producing infectious aerosols (8). Facilities performing such work should have appropriate biosafety precautions in place to prevent exposure to B. anthracis spores; however, anthrax vaccination can be an additional layer of protection in the event of an unrecognized breach in practices or equipment failure. Because of the small potential for inadvertent exposure to aerosolized B. anthracis spores before or after sterility testing, vaccination might also be considered for researchers who routinely work with inactivated B. anthracis suspensions.
In addition, laboratories working with inactivated B. anthracis organisms should develop and implement training activities and incident-response protocols to ensure appropriate actions are taken in the event of a potential exposure. These protocols should describe mechanisms for offering counseling and postexposure chemoprophylaxis and obtaining paired sera from potentially exposed persons. Training at animal research facilities should emphasize prompt communication between animal handlers and researchers if animals are unexpectedly found dead and any special handling procedures are needed for carcasses and bedding. Finally, institutional biosafety committees should routinely review protocols and procedures to ensure that appropriate safety precautions are always in place.