Division of Bacterial Diseases (DBD) News Bulletin
November 3, 2011: Content on this page kept for historical reasons.
TAC: Changing the Way CDC Responds to Outbreaks
The TaqMan® Array Card, known as TAC, (formerly known as the TaqMan® Low Density Array (TLDA) card) is changing the way CDC and the Division of Bacterial Diseases respond to outbreaks. Four Centers at CDC (NCIRD, NCEZID, NCHHSTP, and CGH) are collaborating on optimizing the use of these cards, which became popular after the 2009 H1N1 influenza pandemic.
The premise of TAC is to be able to test for multiple pathogens from a single specimen; at this point, only respiratory specimens have been used. By being able to simultaneously test for multiple pathogens from one specimen, CDC can rapidly identify the etiology of a respiratory outbreak. When the results are suggestive of a certain pathogen, the outbreak specimens are triaged to the appropriate epidemiologists and laboratorians for confirmation testing and to initiate a public health response.
Before TAC was available, each lab at CDC divided a clinical specimen and tested it with their individual wet assays. This testing approach was not only costly (for lab supplies and person time) but also challenging when specimen volumes were minimal, and created a lengthy delay in the turnaround of results. With TAC, the specimen is conserved and testing and response times are significantly shortened. Before TAC, it would take about 20 hours of individual experimental time to analyze 8 clinical specimens for 23 pathogens; with TAC, that time is sliced to approximately 3 hours for similar results.
CDC has been using TAC domestically for the past five years. At this point, laboratorians can look for about 23 pathogens at one time on the card. Jonas Winchell, chief of DBD’s Pneumonia and Response Lab, says, “The huge advantage of TAC is the breadth of organisms you can test for in one specimen.”
With unexplained respiratory disease outbreaks, the card is often called into use unless there is a clear indicator of what pathogen is causing the outbreak. TAC has a high rate of success for focusing the investigation and helped guide responses to outbreaks of C. pneumoniae in Texas, M. pneumoniae in Rhode Island, and adenovirus in Alaska, among others.
Globally, the utility of TAC is being assessed at International Emerging Infections Program (IEIP) field sites along with selected National Influenza Centers (NIC). This is a large pilot study to assess the card’s utility in these settings. TAC is also being used for other international projects, including ones funded by the Bill & Melinda Gates Foundation, like the Aetiology of Neonatal Sepsis in South Asia (ANISA) study.
DBD presented an impressive update on division accomplishments since April during the October 5th QPR with Dr. Frieden and his senior staff. In preparation for QPR, the division reviewed and updated its one and four year goals, identifying 21 new goals for the current fiscal year that involve both domestic and global activities. DBD continues to address initiatives in: reducing pneumococcal disease in the U.S.; controlling pneumonia in developing countries; and introducing conjugate meningococcal vaccine in Africa. In collaboration with other programs within NCIRD, the division will lead a new initiative on utilizing the CDC technology for multi-pathogen testing in public health settings (see TAC story).
IEIP and NIC sites recently had an on-site training at CDC’s headquarters in August where 18 people were trained on how to use TAC with the latest instrument that runs these arrays (see photo). The participants enjoyed the hands-on training and commented that, “The combination of theory, experience of the experts, and the practice was the best combination to learn this technique.”
TAC will likely benefit from further evaluation and optimization, especially for field site use. Winchell envisions an eventual technology transfer of the capability to effectively use TAC, possibly to state health departments. This in turn would alleviate some of the laboratory processing burden of CDC, and allow more time to focus on other pressing issues.
Regards from Rana
I hope you all had a good summer and had the chance to take some time off. The new fiscal year promises to be very exciting for DBD, as we start getting results from many of the studies we began the last few years, embark on new ventures that will increase our understanding of vaccine-preventable diseases and the impact that new vaccines will have in the U.S. and globally.
In the first week of the new fiscal year, as part of QPR, we presented to Dr. Frieden on the TAC assay, an exciting new multi-pathogen respiratory diagnostic platform that is accelerating outbreak control and opening the door for many new investigations in the U.S. and around the world. This highlights yet again the critical role of our laboratories in supporting the division’s work and goals as well as advancing public health. Our critical role is also evident in the many trainings and workshops staff conducted to support the WHO surveillance network that are described in this Bulletin.
We are lucky in our division to have multiple support services for our activities. As you can read about in this Bulletin, we have an excellent statistical unit that is world renowned and has been crucial to our epidemiologic and laboratory activities. Our communications, policy and disease experts staff have contributed significantly to a year-long activity that sought input from the community about meningococcal vaccines as part of a center-wide effort to get more public engagement in vaccines. This activity just concluded with a national stakeholders’ meeting here at CDC.
Though we will be faced with financial and other constraints this fiscal year, I am confident in the ability of our staff to continue to prioritize activities and deliver high quality public health service. I look forward to another fun and productive year!