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After intensive review by the Centers for Disease Control and Prevention (CDC)’s internal Laboratory Safety Improvement Working Group (internal working group), CDC director Tom Frieden, MD, MPH, has lifted the moratorium on a specific type of material transfer for the CDC’s Clinical Tuberculosis Laboratory. The moratorium remains in place for other high-containment (BSL-3 and BSL-4) laboratories. Labs supporting direct patient care are receiving priority review.
The BSL-3 Clinical TB Lab uses a “heat kill” process to inactivate tuberculosis bacteria isolated from patients. It then sends the killed bacteria to a lower-level BSL-2 CDC lab for genetic analysis, rapidly telling clinicians whether their patients carry multi-drug-resistant (MDR) strains of tuberculosis and which drugs will be most effective. Old tests took weeks to yield results; the new test takes only two days.
The plan submitted by the TB lab to the internal working group details safety procedures for each step of the TB inactivation process. The plan includes risk assessment; rules for personal protective equipment; validation (including observation of key steps by a second, highly trained and certified lab technician) that the heat-kill process was conducted correctly and that any living organisms were killed; strict limits on lab access; medical monitoring of lab personnel; and back-up tests. The lab is and has been certified under Clinical Laboratory Improvement Amendments (CLIA) federal standards, and the lab’s testing results and quality-control is reviewed in real time by a CLIA technical supervisor. The TB lab was not one of the two labs involved in recent incidents; those two labs remain closed.
The TB lab’s plan was reviewed and approved by each member of the internal working group; by Michael Bell, MD, CDC’s new director of laboratory safety; and by Frieden.
The internal working group continues its lab-by-lab review of safety procedures. The reviews focus on two main aspects of safety:
• Each lab must demonstrate that its protocols for key control points – such as inactivation of a pathogen – are not only being used but that they are being used by appropriately trained and supervised individuals.
• Each lab is expected to establish redundant controls, similar to the two-key system used in other contexts for critical control points. For example, in the TB lab when heat is used to kill a pathogen, a second trained lab technician will witness the process to make sure the right temperature is used for the right amount of time. Both individuals then sign off on the process.
• As an additional safeguard, there will be unannounced safety inspections–by internal auditors.
No single set of procedures can be used for every lab, as different labs deal with different pathogens and do different kinds of work. Thus safeguards are tailored to each individual lab.
On July 11, 2014, Frieden halted transfer of all biological materials from CDC laboratories in response to incidents in which CDC employees might have been exposed to viable anthrax and in which a highly pathogenic influenza virus contaminated a low pathogenic influenza virus sample sent to a Department of Agriculture high-containment lab. While there appear to have been neither human exposures nor illness as a result of these incidents, CDC immediately undertook a series of remedial actions. These actions include:
• The moratorium on biological material leaving all CDC BSL-3 and BSL-4 labs.
• Appointment of Bell to be director of laboratory safety and serve as the single point of accountability to improve all laboratory safety protocols and practices and procedures; and establishment of the internal working group headed by Bell.
• Reevaluation and improvement of inactivation procedures in all BSL-3 and BSL-4 labs.
• Establishment of an external working group, made up of leading scientists, which will be part of the Advisory Committee to the Director of CDC.
• An investigation to determine the root causes that led to contamination of H5N1 in the influenza laboratory.
• Establishment of a review group under the associate director for science to look at procedures leading to these events and ways to prevent them in the future. This review will be done in conjunction with the internal investigation and in coordination with the external working group.
• Disciplinary action as appropriate for any staff member who knowingly departed from lab safety protocols or who knew about lab safety incidents and didn't report them promptly.
• Considering the implications of these events for the handling of select agents and virulent pathogens more broadly, not just within CDC but throughout the scientific community.