title: Comparison of analytical and clinical performance of three methods for detection of Clostridium difficile.
abstract: BACKGROUND
  Diagnostic laboratory testing for Clostridium difficile infection has undergone considerable and rapid evolution during the last decade. The ideal detection method(s), which should exhibit high analytical and clinical sensitivity and specificity, remains undefined.
  
  
  OBJECTIVE
  We sought to evaluate the analytical and clinical performance characteristics of three methods for the laboratory detection of C difficile.
  
  
  METHODS
  This study used 114 consecutive stool samples to compare three methods of C difficile detection: an enzyme immunoassay (EIA) for toxins A/B, a lateral flow membrane immunoassay for glutamate dehydrogenase (GDH), and a qualitative real-time polymerase chain reaction (PCR) assay. Medical records of all patients having ≥1 positive test result were reviewed to estimate the clinical likelihood of C difficile infection.
  
  
  RESULTS
  Based upon laboratory result consensus values, analytical sensitivity was significantly higher for GDH (94%) and PCR (94%) assays than for toxin EIA (25%). Analytical specificity was significantly higher for PCR (100%) and EIA (100%) than for GDH assay (93%). In contrast, assay performance based upon clinical probability of C difficile infection suggested lower discriminatory power (ie, clinical specificity) of the more analytically sensitive methods.
  
  
  CONCLUSIONS
  Higher rates of C difficile detection will be realized upon implementation of GDH assay and/or real-time PCR-based testing algorithms than by testing with EIA alone. Further study is required to elucidate potential downstream costs for higher detection rates.
authors.affiliation: Clinical Laboratories, Department of Pathology, Robert C.Byrd Health Science Center, West Virginia University Hospitals, Morgantown, WV 26506, USA. plasala@hsc.wvu.edu
authors.forename: P Rocco
authors.initials: PR
authors.lastname: LaSala
authors.forename: Annika M
authors.initials: AM
authors.lastname: Svensson
authors.forename: Amin A
authors.initials: AA
authors.lastname: Mohammad
authors.forename: Peter L
authors.initials: PL
authors.lastname: Perrotta
mesh_terms: D016360:Clostridioides difficile / Q000235:genetics / Q000302:isolation & purification*; D004761:Enterocolitis, Pseudomembranous / Q000175:diagnosis*; D004768:Enterotoxins / Q000032:analysis; D005243:Feces / Q000737:chemistry; D005969:Glutamate Dehydrogenase / Q000032:analysis; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity
chemical_list: D004768:Enterotoxins; D005969:Glutamate Dehydrogenase