*For in vitro Diagnostic Use
|Verigene® C. difficile Test|
|BI/NAP1/027 hypervirulent strain differentiation|
|Instrumentation||Verigene Reader and Processor SP|
|Hands-On Time||<5 minutes|
|Run Time||<2 hours|
Clostridium difficile is a major nosocomial pathogen causing a range of symptoms from mild to severe diarrhea and is the etiological agent of pseudomembranous colitis. The incidence of C. difficile infection has increased markedly in recent years, notably associated with the epidemic spread of the BI/NAP1/027 hypervirulent strain. Accurate diagnosis of C. difficile is essential to ensure patients receive appropriate treatment and that correct infection control measures are put in place.
Nanosphere’s automated Verigene System is uniquely suited to deliver an easy-to-use, multiplexed, cost-effective solution for molecular C. difficile testing. The Verigene C. difficile Test requires less than 5 minutes of user hands-on time to run, and delivers comprehensive results directly from a stool sample in less than two hours.
Load Test Cartridge, test consumables, and sample into Processor SP
Automated sample preparation and test processing on Processor SP
Place slide from Test Cartridge in Verigene Reader for results
"Comparison of Four Culture and Two Nucleic Acid Detection Methods to Toxigenic Culture for the Detection of Toxigenic Clostridium Difficile in Clinical Stool Specimens"Clinical Virology Symposium 201224 April 2012Full dataAbstractIntroduction: Clostridium difficile associated disease affects >500,000 people in the United States alone and results in up to 20,000 deaths. Toxigenic strains of C. difficile produce cytotoxins A and B (TcdA, TcdB), whichcontribute to clinical symptoms. The anti-sigma factor TcdC negatively regulates expression of these toxins. Strains with a mutation in tcdC may express higher levels of toxin, which could result in more severe disease. Early identification of C. difficile strains carrying tcdA, tcdB, and mutations in tcdC in patients suffering diarrheal episodes is critical to management and selection of antibiotic therapy.Methods: A total of 84 stool specimens were collected from patients with suspected C. difficile disease. Each specimen was tested by six methods: i) direct plating to cefoxitin-cycloserine fructose agar (CCFA) and ii) ChromID C. difficile (bioMerieux, Marcy l’Etoile, FR), iii) plating to CCFA and iv) CCFA with horse blood and taurocholate (CCFA-HT) following 24 h enrichment in cycloserine cefoxitin mannitol broth with taurocholate and lysozyme, and tested directly from stool using v) the Xpert C. difficile/Epi (Cepheid, Sunnyvale, CA) and vi) Verigene CDF (Nanosphere Inc, Northbrook, IL) nucleic acid tests. All six results were compared to toxigenic culture as a gold standard.Results: The overall prevalence of toxigenic C. difficile by toxigenic culture was 24% (20/84). The sensitivity of both direct plating methods was low, CCFA: 30.0%, ChromID: 75.0%. Sensitivity of culture improved markedly with 24 h enrichment on both media tested, CCFA: 80.0%, CFFA-HT: 95.0%. Specificity of both direct culture methods was 96.9% while specificity of cultures with pre-enrichment was 92.0-93.0%. The sensitivity of both Xpert and Verigene nucleic acid tests was 90.0% compared to toxigenic culture. The 2 false negative results reported by each system were from the same stool specimens. In each case, both direct culture methods were negative and both enriched culture methods were positive, suggesting a low bacterial burden. Specificity of the Xpert test was 100% and specificity of the Verigene test was 93.8%. Of the 4 false positive results, 2 were positive for tcdB only and 1 was positive for tcdA andtcdB. These were not detected by any of the culture methods. The remaining false positive was tcdA and tcdB positive and was detected by all 4 direct or enriched culture methods but was negative by toxigenic culture. Six specimens (7.1%) were identified by both Xpert and Verigene as containing toxogenic C. difficile harboring a tcdC mutation.Conclusion: The Xpert and Verigene nucleic acid tests for toxigenic C. difficile provide sensitivity comparable to that of enriched culture methods within ~ 2 hrs using minimal hands on time or expertise. Each nucleic acid test provides specific information regarding the presence of cytotoxin tcdB and mutations in tcdC which may lead to increased toxin production. The Verigene test also reports on the presence of the enterotoxin genetcdA.