Friday, December 23, 2016 Written by David Persing M.D., Ph.D., Chief Medical and Technology Officer, Cepheid

From the Editor

Bamboozled

That’s the word that comes to mind when I think of the evolution of C. difficile diagnostic testing over the past decade. The problem has been that commercial tests have evolved in the wrong direction, and lab directors worldwide have been duped into thinking that all was copacetic all along. Indeed, recently published data confirms what treating physicians have known all along—that the toxin immunoassays run in most labs exhibit poor sensitivity and specificity for detection of C. difficile infection. New guidelines from APIC encourage laboratories to return to the original gold standard of toxigenic culture for assessment of C. difficile detection methods. This month’s issue of On-Demand highlights the importance of using a proper reference point when evaluating new technologies. In the case of C.difficile, it is alcohol shock followed by broth enrichment and culture on pre-reduced media. In the case of MRSA detection in blood cultures, conventional susceptibility testing should be used.

In both cases, the use of a true gold standard during the test verification process allows for the most comprehensive understanding of the strengths and weaknesses of a new technology. It also underscores the point that no test, even the one considered to be the gold standard, is perfect. The first article by Dr. Ellen Jo Baron in this issue tackles this subject head on.

A second article by Dr. Fred Tenover documents the progress we have made in establishing a consortium of academic centers interested in tracking Healthcare Associated Infections (the Cepheid HAI Consortium). HAI consortium participants get the benefit of periodic reports and acknowledgement in peer-reviewed publications. By keeping on top of the ever-changing landscape of emerging HAI pathogens, we can make sure that the diagnostic tools used for detecting them now do NOT become less accurate over time.