Cysteine protease Cwp84 (CD2787) as a diagnostic marker for Clostridium difficile
Inventors
DAVIS, MANLI Y. • Lyerly, David M. • Wilkins, Tracy D.
Assignees
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Publication Number
US-8790880-B2
Publication Date
2014-07-29
Expiration Date
Abstract
Accurate and fast detection of the presence of Clostridium difficile (C. difficile) disease is crucial for the proper treatment of patients with C. difficile infection. Present tests detecting the presence of C. difficile disease are fast and cost effective, but are not very sensitive. Using an ELISA including Cell Wall Protein 84 (Cwp84) increases the sensitivity of the ELISA. Cwp84 may be used alone or in combination with other markers to support a diagnosis of C. difficile-associated disease.
Core Innovation
The invention relates to testing a fecal sample from a person for Clostridium difficile by determining whether Cell Wall Protein 84 (Cwp84) is present. The method includes obtaining the fecal sample and determining the presence of Cwp84, and concluding the presence of C. difficile in the fecal sample when Cwp84 is present. It further includes diagnosing the person with active C. difficile infection upon determining the presence of C. difficile in the fecal sample.
The invention is grounded in the use of Cwp84 (Cell Wall Protein 84, CD2787) as a diagnostic antigen marker for C. difficile in patient stool. The partial content states that Cwp84 is conserved and C. difficile-specific, and that cysteine protease activity of Cwp84 includes Cys116 critical activity and a possible C116A variant. The partial content also states that Cwp84 is upregulated by antibiotic exposure and includes defined activity and sequence features including Cys116 and C116A.
The disclosed diagnostic approach is supported by immunoassays using anti-Cwp84 antibodies. The partial content describes an ELISA-based detection approach using anti-Cwp84 antibodies, and includes specific assay performance on clinical fecal samples versus ethanol shock culture. The partial content further states that Cwp84 can be used in combination with GDH in a dual-marker ELISA to improve sensitivity, and that the approach is evaluated across C. difficile ribotypes with a lack of cross-reactivity with non-target bacteria. Device concepts are also described for detecting Cwp84-containing fecal samples.
Claims Coverage
The document provides two independent method claims. Across the independent claims, the core inventive features focus on using Cwp84 presence to determine C. difficile in fecal samples, optionally in combination with GDH, and diagnosing active C. difficile infection accordingly.
Detecting Cwp84 to conclude C. difficile presence and diagnose active infection
Obtain the fecal sample from the person; determine whether Cell Wall Protein 84 (Cwp84) is present in the fecal sample; upon determining Cwp84 is present, conclude the presence of C. difficile in the fecal sample; diagnose the person with active C. difficile infection upon determining the presence of C. difficile in the fecal sample.
Detecting Cwp84 and/or GDH to conclude C. difficile presence and diagnose active infection
Obtain the fecal sample from the person; determine whether C. difficile is present in the fecal sample based on the presence of Cell Wall Protein 84 (Cwp84) and glutamate dehydrogenase (GDH); upon determining the presence of either GDH or Cwp84, conclude the presence of C. difficile in the fecal sample; diagnose the person with active C. difficile infection upon determining the presence of C. difficile in the fecal sample.
The independent claims cover fecal testing workflows that diagnose active C. difficile infection based on determining whether Cwp84 is present, and additionally based on GDH presence as a combined marker. Dependent claims (referenced in the partial content) further refine detection formats and antibody antigen definitions including C116A-related variants.
Stated Advantages
Improved sensitivity when Cwp84 is combined with GDH in a dual-marker ELISA.
High reported assay performance on clinical fecal samples versus ethanol shock culture, including 85% sensitivity and 100% specificity.
Lack of cross-reactivity with non-target bacteria.
Evaluation across multiple C. difficile ribotypes.
Documented Applications
Testing a person’s fecal sample to determine the presence of C. difficile and diagnosing active C. difficile infection.
Device concepts for detecting Cwp84-containing fecal samples.
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