Comparing ImmunoCard with Two EIA Assays for Clostridium difficile Toxins

Edward L Chan; Diane Seales; Hong Drum

doi:10.29074/ascls.22.2.81

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Edward L Chan, PhD⇑
1. Director, Clinical Microbiology, Professor of Pathology, LSU Health Sciences Center, Shreveport, Louisiana
Diane Seales, BS
1. Supervisor, Clinical Microbiology, Clinical Microbiology Laboratory, Trinity Medical Center, Birmingham, Alabama
Hong Drum, MD
1. Pathology resident, Department of Pathology, Trinity Medical Center, Birmingham, Alabama

Address for Correspondence: Edward L Chan, PhD, D(ABMM), FCCM, Director, Clinical Microbiology, LSU Health Sciences Center, 1501 Kings Highway, Shreveport, Louisiana 71130-3932, Phone: (318) 675-7834, echan{at}lsuhsc.edu

Abstract

OBJECTIVE: To compare three Clostridium difficile EIA kits for the detection of C. difficile toxins from clinical specimens.

DESIGN: A total of 287 fresh and stored stool specimens were tested using all three assays. Stools with discrepant results were sent to a reference laboratory for tissue cytotoxin assay.

SETTING: Trinity Medical Center, a community hospital with network hospitals

PATIENTS: Patients with diarrhea submitted stools for detection of C difficile toxins

RESULTS: Of the 287 stool specimens, 116 were positive and 171 negative for C. difficile toxins. The sensitivity, specificity, and positive and negative predictive values of Meridian EIA assay were 99.1, 97.7, 96.6, and 99.4%; ImmunoCard were 100, 98.2, 97.5, and 100%; BioStar OIA assay were 94, 98.8, 98.2, and 96% respectively. ImmunoCard provides the best sensitivity (100%) for C.difficile toxins A and B detection. The BioStar OIA rapid test missed seven positive stool specimens possibly due to failure to detect toxin B.

CONCLUSION: ImmunoCard has slightly higher predictive values, shorter turnaround time and greater convenience compared to the Meridian EIA Assay. ImmunoCard may be cost effective not only in smaller laboratories, but also in high volume laboratories, when used on a STAT basis or single request.

ABBREVIATIONS: C. difficile = Clostridium difficile, EIA = Enzyme Immuno Assay