Testing suitability of Cary-Blair medium for detection of Clostridioides difficile in stool samples by chemiluminiscence immunoassay

Abstract

Clostridioides difficile infection (CDI) is the leading cause of nosocomial diarrhea in developed countries. The chemiluminescence immunoassay (CLIA) for detecting C. difficile requires stool specimens in a dry container, while molecular detection of gastrointestinal pathogens is typically performed using the Cary-Blair transport medium. This discrepancy leads to specimen rejection for CLIA testing. The study aimed to evaluate whether Cary-Blair medium is suitable for detecting glutamate dehydrogenase (GDH) and toxin A/B by CLIA, allowing for a single specimen collection. Therefore, GDH and C.difficile toxin A/B were determined by CLIA, using DiaSorin's LIAISON®, in 85 dry container specimens (58 positive and 27 negative for toxin A/B) from patients with suspected CDI. Then they were transferred to Cary-Blair medium (COPAN FECAL SAWP TM) and the analysis were repeated and compared to those obtained in dry container. Regarding the results, of the 58 positive specimens collected in dry container, 56 remained positive in Cary-Blair, while all negative specimens remained negative on Cary-Blair. Moreover, this medium had a sensitivity of 96.55 % [95 %CI 91.86-100.00], a specificity of 100 %, a PPV of 100 % and a NPV of 93.10 % [95 %CI 83.66-100.00]. Additionally, the experiments repeated 24 h remained highly consistent. In conclusion, Cary-Blair medium was suitable for the determination of C.difficile by CLIA, saving material and analysis time.