Performance of chromID Clostridium difficile Agar Compared with BBL C. difficile Selective Agar for Detection of C. difficile in Stool Specimens

Abstract

We evaluated the performance of a new chromogenic medium for detection of Clostridium difficile, chromID C. difficile agar (CDIF; bioMérieux, France), by comparison with BBL C. difficile Selective Agar (CDSA; Becton Dickinson and Company, USA). After heat pre-treatment (80℃, 5 min), 185 diarrheal stool samples were inoculated onto the two media types and incubated anaerobically for 24 hr and 48 hr for CDIF and for 48 hr and 72 hr for CDSA. All typical colonies on each medium were examined by Gram staining, and the gram-positive rods confirmed to contain the tpi gene by PCR were identified as C. difficile. C. difficile was recovered from 36 samples by using a combination of the two media. The sensitivity with CDIF 48 hr was highest (100%) and was significantly higher than that with CDIF 24 hr (58.3%; P<0.001), because samples with a low burden of C. difficile tended to require prolonged incubation up to 48 hr (P<0.001). The specificity of CDIF 24 hr and CDIF 48 hr (99.3% and 90.6%, respectively) was significantly higher than that of CDSA 48 hr and CDSA 72 hr (72.5% and 67.1%, respectively; P<0.001). CDIF was effective for detecting C. difficile in heat-pretreated stool specimens, thus reducing unnecessary testing for toxin production in non-C. difficile isolates and turnaround time.

Molecular epidemiology and antimicrobial susceptibility of Clostridium difficile isolated from the Chinese People’s Liberation Army General Hospital in China

“…All plates were incubated in a GENbag anaerobic chamber (BioMérieux) at 37 C for 48 h. Colonies of C. difficile were identified by matrix-assisted laser desorption/ionization time-of-flight VITEK mass spectrometry (VITEK MS) with in vitro diagnosis version 2.0 (bioMérieux, France) according to the manufacturer's instructions (Lee et al, 2015;Cheng et al, 2015;Ferreira et al, 2010). The typical colonies are grey to black in colour, with an irregular or smooth border on CDIF (Han et al, 2014).…”

A comparison of Clostridium difficile diagnostic methods for identification of local strains in a South African centre

“…Stool samples were streaked directly onto the agar medium, and plates were incubated at 37 uC for 48 h in an anaerobic chamber under an atmosphere of 5 % H 2 , 10 % CO 2 and 85 % N 2 (Forma Scientific, model 1024). Presumptive C. difficile isolates were selected on the basis of colony morphology rather than on colour due to the fact that some C. difficile strains reportedly do not yield grey/black colonies on ChromID agar (Boseiwaqa et al, 2013;Han et al, 2014;Perry et al, 2010).…”

Evaluation of 3 automated real-time PCR (Xpert C. difficile assay, BD MAX Cdiff, and IMDx C. difficile for Abbott m2000 assay) for detecting Clostridium difficile toxin gene compared to toxigenic culture in stool specimens

“…In addition, the sensitivity of IMDx was significantly lower than the other 2 assays, and this again was mainly due to the much lower sensitivity (37.5%) of IMDx in samples with low burden of C. difficile. Considering that pretreatment by heat shock improves isolation of C. difficile (Lahn et al, 1993) and high recovery rate of CDIF agar (Eckert et al, 2013;Han et al, 2014), we presume that the recovery rate of the toxigenic culture in this study might be higher than other studies. This is supported by the previous study where toxigenic culture with heat treatment was used as the gold standard; the sensitivity of BD GeneOhm C diff was 83.6% (Stamper et al, 2009).…”

“…A 100 μL of this suspension was inoculated onto chromID C. difficile agar (CDIF; bioMérieux, Marcy l'Etoile, France). The plates were incubated at 35°C in a Bactron anaerobic/environmental chamber (Shel Lab, Cornelius, OR, USA) and read after 24 and 48 h (Han et al, 2014). Suspicious colonies were examined by Gram staining, and the gram-positive rods were subjected to PCR to detect the tpi gene, a housekeeping gene of C. difficile and tcdA and tcdB genes (Lemee et al, 2004).…”