Journal of General Practice

4Newer Diagnostic Methods in Clostridium difficile Infection

Abstract

Chetana Vaishnavi

Clostridium difficile infection (CDI) is a public health problem causing severe morbidity and mortality. The clinical presentations of CDI vary from asymptomatic carriage to the full blown pseudo membranous colitis (PMC). With the arrival of the hyper virulent NAP1/BI/027 C. difficile strain, increased incidence of more severe clinical conditions inclusive of PMC, toxic megacolon and intestinal perforation are being reported from the West. Additionally, the recognition of community-acquired CDI signals the presence of several risk factors. Accurate diagnosis of CDI is essential for ongoing epidemiology, optimal treatment and prevention but continues to be challenging. During the past 30 years no standard laboratory test for CDI diagnosis has been clearly established. Diagnostic approaches for CDI are based on several aspects. Clinically the signs and symptoms are watery or bloody diarrhea, abdominal cramps, fever, leukocytosis, etc. PMC can be diagnosed endoscopically as multiple yellow-white friable plaques, a few centimeters in size, attached to the underlying mucosa. Computed tomography scan findings does not help diagnosis, but may help in initiating specific therapy against CDI. Culture can be used for epidemiological and antibiogram purposes during outbreaks. Tissue cultures, enzyme immunoassays and molecular assays are useful to detect C. difficile toxins. Glutamate dehydrogenase test helps to screen out a large number of samples. Toxigenic culture is based on the isolation of C. difficile in culture and then detecting its toxigenic status. The implications of a false negative or a false positive test can lead to disastrous consequence. There are currently two reference assays for the diagnosis of CDI with different targets: the cytotoxicity assay that detects free toxins and the toxigenic culture which detects the organism with the potential to produce toxin. CDI diagnostic testing is an important issue and clinical laboratory professionals should use the assays which give the best performance for the detection of CDI.