A study on clinical application of a novel reagent detecting toxigenic strains of Clostridium difficile

Abstract

Objective: To evaluate the performances of a "ready-to-use" liquid chromogenic medium for detecting toxigenic strains of C. difficile from stool specimens, by comparing with the reference method of combined GeneXpert detection with MALDI-TOF MS identification. Methods: This study was a clinical application research. A total of 322 stool specimens from patients with diarrhea in Henan Provincial People's Hospital were detected by using this liquid chromogenic mediumor by combination of GeneXpert and MALDI-TOF MS identification after CCFA culture from March to November 2017. The reference method was combined GeneXpert detection with MALDI-TOF MS identification. Data were analyzed with kappa analysis by use of SPSS 13.0. In this study, the limit of detection and anti-interference capability of chromogenic medium were determined with standard strains. Results: This assay had a sensitivity of 92.86% (52/56), a specificity of 96.99% (258/266), a positive predictive value of 86.67% (52/60), and a negative predictive value of 98.47% (258/262). Furthermore, this assay was well consistent with the reference method (kappa=0.874, P<0.01). The limit of detection of this assay was 10(3) CFU/ml for toxigenic strain of ATCC9689, and there was no interference by non-toxigenic strain of ATCC43593 or Clostridium perfringens (ATCC13124) even.When the concentration of ATCC9689 was as low as 0.5 McFarland. Conclusions: It is worth expanding clinical research for this "ready-to-use" chromogenic medium and preparing for its popularization in primary medical institutions, due to its similar performance to the reference method for detecting toxigenic strains of C. difficile, simple operation and no need of anaerobic condition.