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12:58
A Protocol to Characterize the Morphological Changes of Clostridium difficile in Response to Antibiotic Treatment
Published on: May 25, 2017
Differences in outcome according to Clostridium difficile testing method: a prospective multicentre diagnostic
Timothy D Planche1, Kerrie A Davies, Pietro G Coen
1Centre for Infection and Immunity, Division of Clinical Medicine, St George's, University of London, London, UK; Department of Medical Microbiology, St George's Healthcare NHS Trust, London, UK.
The Lancet. Infectious Diseases
|September 7, 2013
Summary
Diagnosis of Clostridium difficile infection (CDI) is complex. The cytotoxin assay, detecting toxin, best defines true CDI cases and correlates with patient outcomes, unlike mere bacterial presence.
Area of Science:
- Clinical microbiology
- Infectious disease diagnostics
- Healthcare epidemiology
Background:
- Clostridium difficile infection (CDI) diagnosis is challenging due to varied laboratory methods.
- Cytotoxigenic culture detects toxigenic bacteria (including colonization), while cytotoxin assay detects active toxin.
Purpose of the Study:
- To validate reference diagnostic methods for CDI against clinical outcomes.
- To develop an optimal laboratory diagnostic algorithm for CDI.
Main Methods:
- Prospective, multicentre study involving 12,420 faecal samples.
- Compared cytotoxigenic culture and cytotoxin assays with clinical data (mortality, hospital stay).
- Utilized tests for bacterium, toxins, and toxin genes.
Main Results:
- Mortality was significantly higher in patients positive for cytotoxin assay (Group 1) compared to those negative for cytotoxin assay but positive for cytotoxigenic culture (Group 2) or those negative for both (Group 3).
- Multivariate analysis confirmed increased mortality risk for Group 1 versus Group 3.
- Multistage diagnostic algorithms outperformed standalone assays.
Conclusions:
- Toxin detection via cytotoxin assay is the most reliable indicator of true CDI and correlates with clinical outcomes.
- Presence of toxigenic Clostridium difficile alone does not increase mortality.
- A new category, 'potential CDI excretor' (toxigenic culture positive, cytotoxin assay negative), can identify asymptomatic carriers who pose an infection risk.
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