Expert Access - Molecular Tools for Diagnosis and Management of C. difficile Infection

Eileen Burd

Eileen M. Burd, PhD, DABMM

June 23, 2011
1:00-2:00 pm Eastern (U.S.) time



Molecular Tools for Diagnosis and Management of C. difficile Infection

Infection with C. difficile results in a spectrum of disease ranging from asymptomatic carriage to serious conditions such as pseudomembranous colitis and toxic megacolon. Because the organism can form spores, it is difficult to remove from the hospital environment and nosocomial spread continues to be of concern. In addition, severe cases of infection caused by a new epidemic stain of C. difficile are appearing in populations in the community that have previously been considered not to be at risk. Rapid and accurate diagnosis of C. difficile infection is important for treatment of infected patients and prevention of spread.

There are a number of laboratory tests available for diagnosing C. difficile infection. The introduction of nucleic acid amplification assays is shifting what is considered to be the optimal approach. The gold standard diagnostic test is toxigenic culture and although the sensitivity and specificity of this test are high, it is not commonly used because of complexity and long turnaround time. The cell culture cytotoxin assay also is being less frequently used. Laboratories have more commonly used one of a variety of enzyme immunoassays (EIAs), which detect toxin A or both toxins A and B, but are now recognized as not being adequately sensitive to be used alone. Various two-step and three step algorithms have been developed that use glutamate dehydrogenase (GDH) assays as an initial screen for C. difficile followed by toxin EIA and/or a nucleic acid amplification assay to confirm positive GDH results. These algorithms have been called into question because the sensitivity of GDH assays may not be adequate. Several nucleic acid amplification assays are now commercially available and many laboratories are using or considering use of these assays as stand-alone tests.


Eileen M. Burd, PhD, DABMM, is Director of Clinical Microbiology in the Department of Pathology and Laboratory Medicine at Emory University Hospital in Atlanta, GA. The Emory University Microbiology Laboratory is a centralized, full-service laboratory that serves the four hospitals currently in the Emory Healthcare System. Dr. Burd also holds a faculty appointment as Associate Professor at Emory University School of Medicine with a primary appointment in the Department of Pathology and Laboratory Medicine and a secondary appointment in the Department of Medicine, Division of Infectious Diseases. She received her PhD degree from the Medical College of Wisconsin in Milwaukee, and completed post-doctoral and clinical infectious disease fellowships at the Medical College of Wisconsin, as well. She was the Division Head of Microbiology at Henry Ford Hospital in Detroit, MI, for 12 years prior to joining the faculty at Emory University in 2007. Her primary focus is the laboratory diagnosis and management of patients with infectious diseases. She is also actively involved in medical education and has varied research interests surrounding the nature of etiologic agents and the diagnosis and epidemiology of infectious diseases.

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