Vidas clostridium difficile a b

Thirty-four Lactobacillus spp. isolated from infant feces were analyzed in this study (Additional file 1). All lactobacilli were routinely cultured in an anaerobic chamber (Concept Plus, Ruskinn Technology, UK) (10% CO₂, 10% H₂, and 80% N₂) for 24 h at 37°C in de Man, Rogosa, Sharpe (MRS) medium (Oxoid, England).
A C. difficile isolate, designated strain B2-CU-0001-54 was obtained from feces of an infected patient positive for C. difficile toxins A and B by VIDAS® Clostridium difficile A & B (Biomérieux, France) at the Department of Microbiology, Faculty of Medicine, Chulalongkorn University. This strain is positive for TcdA and TcdB as determined by PCR for toxin A and B genes [70 (link)] and the reactivity with mouse anti-TcdA and anti-TcdB monoclonal antibodies (Meridian Life Science, Inc.). C. difficile B2-CU-0001-54 was routinely cultured anaerobically on Brucella agar (Oxoid, England) at 37°C for 48 h. Cells were harvested, re-suspended in McCoy’s medium, and adjusted to a McFarland 6 standard (1.8×10⁹ cells/mL) prior to co-culture with HT-29 cells. This study was approved by the Ethics Committee of Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand (COA no.617/2011, IRB no.246/54). Written informed parental consent for fecal samples was obtained from participants.

Stool specimens sent to PHE Microbiology services-Cambridge from the East of England region were collected over a 17 month period (July 2010 to November 2011) and stored at -20°C. For this evaluation study we sought to include at least 100 known C. difficile positive stool specimens balanced with around the same number of negative specimens. Such a sample size would provide a 95% confidence interval of +/– 5.9% for an estimated test sensitivity (or specificity) of 90%, which is in line with recommended guidelines [40] (link). Of 218 stool specimens selected consecutively over the study period with sufficient volume to permit multiple testing, 196 were unformed and 22 were solid. The status of these samples had already been determined by VIDAS® Clostridium difficile A & B (bioMérieux, FR), toxigenic cell culture assay, culture and ribotyping, and comprised 111 C. difficile toxin positives and 107 negatives, and provided the gold standard reference test result for benchmarking. A broad range of different ribotypes were observed in the positive specimen group and are detailed below. Specimens were assigned numbers unique to the study and were blinded and aliquoted for the study.