Rare discrepancy in the result of enzyme immunoassay in a patient infected by Clostridioides difficile

Clostridioides (Clostridium) difficile produces glutamate dehydrogenase (GDH) in large amounts, which is frequently used to screen C. difficile infection (CDI). Generally, the sensitivity of GDH–enzyme immunoassay (GDH–EIA) is significantly higher than that of the toxin EIA. In this report, we describe an extremely rare case of discrepancy in EIA with GDH-negative and toxin-positive results. Nucleic acid amplification revealed toxin B gene, binary toxin gene, and tcdC deletion. Additionally, the growth of C. difficile was monitored by culture method, which showed positive result for GDH. These findings indicate that laboratory diagnosis of CDI is challenging. Therefore, the results should be carefully interpreted considering the patient’s clinical course.