engleski

Advances in Clostridioides difficile diagnostics

Clostridioides difficile infections (CDI) are among the most common hospital-acquired infections in highly developed countries. The most important challenge in diagnostic is choosing the accurate test with high sensitivity and specificity Clostridioides difficile is an opportunistic pathogen and it’s important to distinguish colonization from infection. Therefore, only diarrheal stool from symptomatic patients should be tested. Many different testing methods are available today (immunoenzymatic, immunochromatographic and molecular). Some tests detect specific bacterial antigen GDH (glutamate dehydrogenase), production of toxins A/B or the existence of a toxigenic region in the bacterial genome. In 2009, the European Society of Clinical Microbiologists and Infectious Disease (ESCMID) published the first guidelines for the diagnosis of CDI and proposed the introduction of a two-step algorithm. In the first step, screening test with high NPV (negative predictive value) is used, such as rapid immuno-enzyme assay (EIA) for GDH antigen. GDH positive specimens are then tested with a confirmatory EIA or nucleic acid amplification test (NAAT) for evidence of free toxins A/B or toxigenic chromosomal region. Sometimes both tests (evidence of toxigenic region and active toxin production) are used. Control testing (test of cure) is not recomended as patients may be colonized for months. Since the introduction of two-step algorithm, CDI diagnostic has been fairly standardized, but different laboratories use different tests, so it’s sometimes difficult to compare results. Therefore, the guidelines were updated in 2016 and 2018, and ESCMID's two / three-step algorithm was confirmed as optimal choice in CDI diagnostics. The presence of free toxins in the stool of patients better correlates with symptomatic CDI and poor outcome, while molecular tests can detect asymptomatic carriers that have no symptoms and do not require any intervention or treatment.

C. difficile diagnostic

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