Laboratories face a multitude of challenges in diagnostic testing for Clostridium difficile. Some of the more advanced technologies such as polymerase chain reaction (PCR) have actually complicated the process of appropriately diagnosing and treating C. difficile infection (CDI). 

An AACC webinar on April 21, “Addressing Challenges in the Laboratory Diagnosis of C. difficile,” seeks to provide some clarity on this issue and offer a game plan for labs on developing effective C. difficile testing in their institutions. 

“It should be noted that CDI is a clinical diagnosis that can be supported by clinical and endoscopic findings,” Carey-Ann Burnham, PhD, ABMM, associate professor of pathology and immunology and pediatrics at Washington University School of Medicine in St. Louis, Missouri, told CLN Stat. 

She and fellow speaker Peter H. Gilligan, PhD, professor of microbiology and immunology and pathology and laboratory medicine at the University of North Carolina School of Medicine in Chapel Hill, will discuss the latest research on this topic and the steps labs should take to properly perform and report on C. difficile tests. 

Laboratory support for diagnosing CDI has evolved tremendously over the last 10 years, Burnham continued. Right now, nucleic-acid detection based methods to detect C. difficile toxin genes are the most common methods in use. 

“While these methods are analytically sensitive and specific, they do not differentiate colonization from disease. Thus, if the tests are not deployed in a judicious manner, clinical specificity may be compromised. This can have important clinical implications—paradoxically, the antimicrobial therapies used to treat CDI can also precipitate CDI,” Burnham said.

Unsurprisingly, a great deal of controversy surrounds the “best” test for diagnosing CDI. That said, Burnham emphasizes that labs play a significant role in guiding best practices for C. difficile testing.

Laboratory professionals should educate themselves on the strengths and limitations of C. difficile assays. Burnham emphasized that testing should only be conducted on those individuals with clinically significant diarrhea who don’t have another obvious reason to present with such symptoms (such as recent laxative use or tube feeds).

Labs should have policies in place that prohibit C. difficile testing on formed stool and that limit repeat testing.

“There is a common dogma of ordering C. difficile testing three times. This practice should be discouraged. With each round of testing, the number of false positive results will exceed the number of true positive results,” Burnham said. Laboratories should also consider restricting C. difficile testing on neonates, as “very high rates of C. difficile colonization are observed in this patient population.” 

Register online to attend this informative webinar on C. difficile and earn 1.0 ACCENT credit.