Anti-C. difficile Glutamate Dehydrogenase polyclonal antibody

This study aimed at evaluating in outpatients an algorithm for the laboratory diagnosis of Clostridioides (Clostridium) difficile infection (CDI), i.e., enzyme immunoassays (EIAs) detecting bacterial glutamate dehydrogenase (GDH) and toxin A/B, followed by polymerase chain reaction (PCR) analyses of samples with discordant EIA results. In total, 9802 examinations of stool samples by GDH and toxin EIAs performed in 7263 outpatients and 488 inpatients were analyzed retrospectively. Samples with discordant EIA results had been tested by a commercially available PCR assay detecting genes of the C. difficile-specific those phosphate isomerase (tpi) and toxin B (tcdB). Concordant EIA results (686 C. difficile-positive, 8121 negative) were observed for 8807 (89.8%; 95% CI, 89.290.4%) samples. Of 958 samples with discordant EIA results, 895 were analyzed using PCR and 580 of 854 GDH-positive/borderline, toxin-negative samples (67.9%; 95% CI, 64.7-71.0%) were positive for tpi and tcdB, while 274 samples (32.1%; 95% CI, 29.0-35.3%) were tcdB-negative. In contrast, 35 of 41 GDH-negative, toxin-positive/borderline samples (85.4%; 95% CI, 71.2-93.5%) were tcdB-negative. Still, 6 samples (14.6%; 95% CI, 6.5-28.8%) yielded positive PCR results for both genes. In conclusion, around 90% of the samples were analyzed appropriately by only applying EIAs. Approximately one third of the PCR-analyzed samples were tcdB-negative; thus, patients most likely did not require CDI treatment.

Objectives: To evaluate the performance of the GeneXpert C. difficile assay and C. diff Quik Chek Complete (QCC) kit for the detection of toxins from fecal specimens and cooked meat broth (CMB) culture using toxigenic stool culture as reference method, for the diagnosis of C. difficile infection (CDI) in a community setting. Methods: Non-repeat stool samples were tested simultaneously by GeneXpert and QCC. Toxin detection was done on neat stool samples, inoculated CMB, and isolated colonies. Results: Nineteen (4.6%) of 409 samples were positive for glutamate dehydrogenase (GDH) in stool and CMB by the QCC assay; seven (1.7%) were positive for both GDH and toxins A/B. The sensitivities of QCC to detect C. difficile toxin directly in stool specimens and CMB were 68.4% and 100%, respectively, while specificities were 100% and 83%, respectively. C. difficile toxin was detected in 10 (2.5%) specimens and 13 (3.2%) CMB. Thirteen (68.4%) of 19 isolates were positive for C. difficile toxin by GeneXpert and QCC and were taken as the reference toxigenic culture. The disease burden was thus 3.2%. The sensitivities of GeneXpert in stool and CMB were 81.3% and 100%, respectively, while specificities were 100% and 100%, respectively. Conclusion: The GeneXpert assay was more sensitive than QCC for the detection of C. difficile toxin in stool, but both assays were highly specific. (C) 2014 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.