Comparison of two commercial molecular tests for the detection of Clostridium difficile in the routine diagnostic laboratory

Zidaric, Valerija; Kevorkijan, Božena Kotnik; Orešič, Nadja; Janežič, Sandra; Rupnik, Maja

doi:10.1099/jmm.0.030163-0

Cited by 27 publications

(15 citation statements)

References 25 publications

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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: 89%

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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confidence: 89%

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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“…LAMP was used for diagnostic purposes in all the studies and not for screening patients. The quality of studies as assessed by the QUADAS-2 tool was generally high, with all but one study [35] meeting 6 or more of the criteria (Supplementary figure 1A and 1B). Three studies [28,36,37] used CCNA as a reference test.…”

Section: Study Characteristicsmentioning

confidence: 99%

“…After reviewing the titles and abstracts, 21 articles were selected for full-text evaluation (Figure 1). Sixteen articles with 18 studies published between 2005 and 2014 reported the sensitivity and specificity of LAMP on stool samples for the diagnosis of C. difficile infection, and were included in our meta-analysis [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Five articles were excluded (reasons for exclusion in Figure 1).…”

Section: Study Characteristicsmentioning

confidence: 99%

Accuracy of loop-mediated isothermal amplification for the diagnosis of Clostridium difficile infection: a systematic review

Lloyd

Pasupuleti

Thota

et al. 2015

Diagnostic Microbiology and Infectious Disease

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CitationLloyd A, Pasupuleti V, Thota P, Pant C, Rolston DDK, Hernandez A V., et al. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT

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“…With regard to false negatives, two patients tested positive just hours after the initial negative test, which is strongly suggestive of false-negative results, especially since both of these patients had clinical evidence of C. difficile-associated diarrhea. Prior studies have shown the Cepheid Xpert C. difficile PCR assay to have a sensitivity of 96 to 97% (8)(9)(10)(11), so a significant number of false negatives should be expected in a laboratory that performs thousands of tests annually; the overall prevalence of CDI for inpatients at New York-Presbyterian Hospital, Columbia University Medical Center (NYPH/CUMC) was 1.6% in the year 2013. Furthermore, many patients with suspected CDI receive empirical antimicrobial therapy prior to stool sample collection, which can potentially lead to an increased rate of false-negative results.…”

Section: Discussionmentioning

confidence: 99%

Clinical Characteristics of Patients Who Test Positive for Clostridium difficile by Repeat PCR

et al. 2014

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The high sensitivity of PCR assays for diagnosing Clostridium difficile infection (CDI) has greatly reduced the need for repeat testing after a negative result. Nevertheless, a small subset of patients do test positive within 7 days of a negative test. The aim of this study was to evaluate the clinical characteristics of these patients to determine when repeat testing may be appropriate. The results of all Xpert C. difficile PCR (Cepheid, Sunnyvale CA) tests performed in the clinical microbiology laboratory at New York-Presbyterian Hospital, Columbia University Medical Center (NYPH/CUMC) from 1 May 2011 through 6 September 2013, were reviewed. A retrospective case-control study was performed, comparing patients who tested positive within 7 days of a negative test result to a random selection of 50 controls who tested negative within 7 days of a negative test result. During the study period, a total of 14,875 tests were performed, of which 1,066 were repeat tests (7.2%). Eleven of these repeat tests results were positive (1.0%). The only risk factor independently associated with repeat testing positive was history of a prior CDI (odds ratio [OR], 19.6 [95% confidence interval {CI}, 4.0 to 19.5], P < 0.001). We found that patients who test positive for C. difficile by PCR within 7 days of a negative test are more likely to have a history of CDI than are patients who test negative with repeat PCR. This finding may be due to the high rate of disease relapse or the increased likelihood of empirical therapy leading to false-negative results in these patients. The incidence of Clostridium difficile infection (CDI) has been rising over the last 2 decades, leading to significant morbidity and mortality, particularly in elderly and hospitalized patients (1). PCR assays for the diagnosis of CDI have gained in popularity in clinical microbiology laboratories in recent years. These PCR tests are rapid, simple to perform, and offer a high degree of sensitivity and specificity for detecting toxigenic C. difficile strains, usually by detection of the tcdB gene that encodes toxin B production. The high sensitivities of these assays have greatly reduced the need for repeat testing after a negative result, especially within the first 7 days of a negative result. Multiple studies have demonstrated that repeat testing within 7 days yields positive results in only about 1 to 3% of cases (2-5). However, clinical microbiology laboratories continue to receive test requests for patients with a recent negative test result, presumably in part due to the perceived poor sensitivity of previously used enzyme immunoassays (EIAs). These unnecessary PCR tests lead to increased costs and inefficient utilization of resources.Our laboratory began using PCR testing for C. difficile on 1 May 2011, and due to the low yield of repeat testing, instituted a policy on 30 October 2013 to reject stool specimens received within 7 days of a negative PCR result unless permission was granted by the laboratory director. Despite the low probability of a positive ...

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Comparison of two commercial molecular tests for the detection of Clostridium difficile in the routine diagnostic laboratory

Cited by 27 publications

References 25 publications

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

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

Accuracy of loop-mediated isothermal amplification for the diagnosis of Clostridium difficile infection: a systematic review

Clinical Characteristics of Patients Who Test Positive for Clostridium difficile by Repeat PCR

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