Evaluation of the Xpert Clostridium difficile Assay for the Diagnosis of Clostridium difficile Infection

Shin, Saeam; Kim, Minkyung; Kim, Myung-Sook; Lim, Hee‐Jung; Kim, Heejung; Lee, Kyungwon; Chong, Yunsop

doi:10.3343/alm.2012.32.5.355

Cited by 45 publications

(21 citation statements)

References 15 publications

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“…Assay characteristics did not, however, differ significantly. The data for the BD MAX Cdiff assay were comparable to those from a previous study (7), and both molecular assays confirmed the high sensitivity and specificity rates of C. difficile PCR assays (3,5,(14)(15)(16)(17)(18). Also, no differences were observed when the Xpert C. difficile and the BD GeneOhm Cdiff assays were compared (19); thus, equal performance of all three assays can be assumed.…”

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confidence: 73%

Evaluation of the Fully Automated BD MAX Cdiff and Xpert C. difficile Assays for Direct Detection of Clostridium difficile in Stool Specimens

et al. 2013

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We evaluated the fully automated molecular BD MAX Cdiff assay (BD Diagnostics) and the Xpert C. difficile test (Cepheid) for rapid detection of Clostridium difficile infection. Culture was done on chromogenic agar followed by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry identification and toxin detection. Repeat testing was required for 1.8% and 6.0% of the BD MAX and Xpert tests, respectively. Sensitivities, specificities, positive predictive values (PPV), and negative predictive values (NPV) were 90.5%, 97.9%, 89.3%, and 98.1%, respectively, for BD MAX and 97.3%, 97.9%, 90.0%, and 99.5%, respectively, for Xpert. Clostridium difficile is the most important cause of hospitalacquired diarrhea. To implement timely infection control measures and appropriate treatment, rapid identification of toxigenic C. difficile is necessary (1). However, laboratory diagnostics remain challenging, as rapid test procedures relying on enzyme immunoassays (EIAs) show limited sensitivity (2), whereas the more-sensitive toxigenic culture and cytotoxicity assays are demanding and time-consuming. Two-step algorithms consisting of sensitive detection of glutamate dehydrogenase followed by a confirmatory toxin test have been proposed (2-4), yet the actual sensitivity has been questioned (5). Nucleic acid amplification techniques have been developed to combine low turnaround times with high sensitivity (6), but these assays require specific infrastructure. More recently, fully automated PCR assays that combine nucleic acid extraction, amplification, and detection have been developed. The Xpert C. difficile assay (Cepheid, Sunnyvale, CA) has high sensitivity and specificity and allows for accurate and rapid detection of Clostridium difficile infection (CDI). Recently, the BD MAX platform (BD Diagnostics, Franklin Lakes, NJ) has been made available; this allows for processing up to 24 samples in a fully automated PCR system. Clinical evaluation of the BD MAX Cdiff assay, based on detection of tcdB, has been published only for comparison with the BD GeneOhm assay (7).This study was conducted between April and July 2012 at the 2,000-bed tertiary care University Hospital Heidelberg. From 333 individual patients, 448 stool specimens, mostly (94.9%) soft or liquid, were examined. Samples were analyzed upon delivery or after overnight storage at 4°C. Specimens were analyzed by the BD MAX Cdiff assay and the Xpert C. difficile test. The standard technique used by the microbiology laboratory as the routine assay was the toxin A/B EIA (miniVIDAS; bioMérieux, Marcy l'Etoile, France). For the BD MAX Cdiff assay, stool samples were vortexed for 15 s and a 10-l loop was used to inoculate the sample tube. The Xpert C. difficile test and the miniVIDAS assay were done strictly in accordance with the manufacturers' protocols. As the reference method (8), stool samples were streaked onto chromID C. difficile agar plates (bioMérieux), incubated anaerobically at 35°C, and read after 24 and 48 h (9, 10). Suspicious col...

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confidence: 73%

Evaluation of the Fully Automated BD MAX Cdiff and Xpert C. difficile Assays for Direct Detection of Clostridium difficile in Stool Specimens

et al. 2013

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“…The superscript b after GenϪ/Xpϩ (4.9%) indicates that one culture-positive specimen had a borderline result using the GenomEra C. difficile assay both on the first test and on retest; therefore, the final molecular result was considered negative. (10,15,(17)(18)(19)(20)(21)(22)(23)(24)(25), we found only 1 study evaluating it with the same algorithm as ours and using toxigenic culture as the gold standard (15). The authors found that the Se, Sp, PPV, and NPV of the algorithm were 86.1%, 97.8%, 88.6%, and 97.2%, respectively.…”

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confidence: 90%

“…Diff Quik Chek Complete (QC) (TechLab, Blacksburg, VA, USA) detects by immunochromatography both GDH and toxins A and B as a single procedure device (4). The real-time PCR assay Xpert C. difficile assay (Xpert) (GeneXpert; Cepheid, Sunnyvale, CA, USA) that detects the toxin B gene (tcdB), binary toxin genes, and tcdC 117-nucleotide (nt) deletion (epidemic 027 ribotype) is frequently used as a confirmatory test because of its speed and good internal validity values (7)(8)(9)(10)(11).…”

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confidence: 99%

Comparison of GenomEra C. difficile and Xpert C. difficile as Confirmatory Tests in a Multistep Algorithm for Diagnosis of Clostridium difficile Infection

Alcalá¹,

Reigadas²,

Marı́n³

et al. 2015

J Clin Microbiol

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We compared two multistep diagnostic algorithms based on C. Diff Quik Chek Complete and, as confirmatory tests, GenomEra C. difficile and Xpert C. difficile. The sensitivity, specificity, positive predictive value, and negative predictive value were 87.2%, 99.7%, 97.1%, and 98.3%, respectively, for the GenomEra-based algorithm and 89.7%, 99.4%, 95.5%, and 98.6%, respectively, for the Xpert-based algorithm. GenomEra represents an alternative to Xpert as a confirmatory test of a multistep algorithm for Clostridium difficile infection (CDI) diagnosis. R apid diagnosis of Clostridium difficile infection (CDI) is crucial for optimal disease control (1, 2). For this reason, many microbiology laboratories used sensitive algorithms based on enzyme immunoassay (EIA) for detection of glutamate dehydrogenase (GDH) with EIA detection of toxins A and B, followed by a confirmatory test based on toxin A or B gene amplification (3-6).C. Diff Quik Chek Complete (QC) (TechLab, Blacksburg, VA, USA) detects by immunochromatography both GDH and toxins A and B as a single procedure device (4). The real-time PCR assay Xpert C. difficile assay (Xpert) (GeneXpert; Cepheid, Sunnyvale, CA, USA) that detects the toxin B gene (tcdB), binary toxin genes, and tcdC 117-nucleotide (nt) deletion (epidemic 027 ribotype) is frequently used as a confirmatory test because of its speed and good internal validity values (7-11).The new assay, GenomEra C. difficile (GenomEra) (Abacus Diagnostica, Turku, Finland), is a promising amplification system that detects the tcdB gene in approximately 1 h using rapid thermal cycling by means of a multiblock thermal cycler and homogeneous time-resolved fluorescence detection technology using lanthanide chelates which has proved to be resistant to background effects (12). This molecular method has the CE mark but is not cleared at this moment by the FDA.The purpose of this study was to compare the diagnostic accuracy of two algorithms based on QC as the screening test and Xpert or GenomEra as confirmatory tests for the rapid diagnosis of CDI.From October 2012 to March 2013, all loose stool specimens sent to the laboratory of the Hospital General Universitario Gregorio Marañón (Madrid, Spain) for CDI diagnosis were tested in parallel with the direct cytotoxicity assay, toxigenic culture, and the two multistep algorithms evaluated. The gold standard was the combination of direct cytotoxicity assay with stool specimens and cytotoxicity assay with isolates as previously described (13). The multistep algorithm consisted of an initial test, QC, performed according to the manufacturer's recommendations. Specimens positive for both GDH and toxins were considered positive, while specimens negative for both antigens were considered negative. Specimens with uncertain (GDH-positive and toxin-negative) results were tested in parallel using Xpert and GenomEra for confirmation. Xpert was performed according to the manufacturer's recommendations. GenomEra was performed by diluting 1 l of sample in a tube with 1 ml of sample buffer...

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“…In comparison to toxigenic cultures, they found the sensitivity, specificity, positive and negative predictive values to be 100%, 94.6%, 83.1%, and 100%, respectively, for the Xpert Clostridium difficile assay and 40.8%, 98.0%, 100%, and 88.9%, respectively, for VIDAS based assay. 8 In conclusion, CDI is not so common in India. However, we need to look it as an etiological agent in Antibiotic associated diarrhoea (AAD) especially in critically ill patients.…”

Section: Resultsmentioning

confidence: 99%

Role of rapid detection of Clostridium difficile toxin gene versus its expression in symptomatic patients with suspected CDI in a tertiary care hospital in India

Rani¹,

Sardana²,

Mendiratta³

et al. 2016

Int.J.Curr.Microbiol.App.Sci

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Evaluation of the Xpert Clostridium difficile Assay for the Diagnosis of Clostridium difficile Infection

Cited by 45 publications

References 15 publications

Evaluation of the Fully Automated BD MAX Cdiff and Xpert C. difficile Assays for Direct Detection of Clostridium difficile in Stool Specimens

Evaluation of the Fully Automated BD MAX Cdiff and Xpert C. difficile Assays for Direct Detection of Clostridium difficile in Stool Specimens

Comparison of GenomEra C. difficile and Xpert C. difficile as Confirmatory Tests in a Multistep Algorithm for Diagnosis of Clostridium difficile Infection

Role of rapid detection of Clostridium difficile toxin gene versus its expression in symptomatic patients with suspected CDI in a tertiary care hospital in India

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