Multicenter Evaluation of a New Screening Test That Detects
            <i>Clostridium difficile</i>
            in Fecal Specimens

Zheng, Limin; Keller, Sylvia; Lyerly, David M.; Carman, Robert J.; Genheimer, Christopher W.; Gleaves, Curt A.; Kohlhepp, Sue J.; Young, S.; Pérez, Sebastián; Ye, K.

doi:10.1128/jcm.42.8.3837-3840.2004

Cited by 66 publications

(44 citation statements)

References 24 publications

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“…This highlights the high negative predictive value of the GDH screen relative to culture, which has also been evaluated relative to CCNA (31,34,37). GDH screening is less specific, which may reflect antigenic homology among clostridia, as was suggested by a false-positive rapid stool toxin test result for a patient with Clostridium sordellii bacteremia (13).…”

Section: Discussionmentioning

confidence: 99%

Yield of Stool Culture with Isolate Toxin Testing versus a Two-Step Algorithm Including Stool Toxin Testing for Detection of Toxigenic Clostridium difficile

Reller¹,

Lema²,

et al. 2007

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We examined the incremental yield of stool culture (with toxin testing on isolates) versus our two-step algorithm for optimal detection of toxigenic Clostridium difficile. Per the two-step algorithm, stools were screened for C. difficile-associated glutamate dehydrogenase (GDH) antigen and, if positive, tested for toxin by a direct (stool) cell culture cytotoxicity neutralization assay (CCNA). In parallel, stools were cultured for C. difficile and tested for toxin by both indirect (isolate) CCNA and conventional PCR if the direct CCNA was negative. The "gold standard" for toxigenic C. difficile was detection of C. difficile by the GDH screen or by culture and toxin production by direct or indirect CCNA. We tested 439 specimens from 439 patients. GDH screening detected all culture-positive specimens. The sensitivity of the two-step algorithm was 77% (95% confidence interval [CI], 70 to 84%), and that of culture was 87% (95% CI, 80 to 92%). PCR results correlated completely with those of CCNA testing on isolates (29/29 positive and 32/32 negative, respectively). We conclude that GDH is an excellent screening test and that culture with isolate CCNA testing detects an additional 23% of toxigenic C. difficile missed by direct CCNA. Since culture is tedious and also detects nontoxigenic C. difficile, we conclude that culture is most useful (i) when the direct CCNA is negative but a high clinical suspicion of toxigenic C. difficile remains, (ii) in the evaluation of new diagnostic tests for toxigenic C. difficile (where the best reference standard is essential), and (iii) in epidemiologic studies (where the availability of an isolate allows for strain typing and antimicrobial susceptibility testing).Since its identification in 1978, Clostridium difficile has emerged as the predominant cause of antibiotic-associated colitis and the leading cause of diarrhea in hospitalized patients (4). Strains of C. difficile can be toxigenic or nontoxigenic; however, only toxigenic strains produce disease. The two main virulence factors are toxin A, a 308-kDa enterotoxin with some cytopathic effects (TcdA), and Toxin B (TcdB), a potent 270-kDa cytotoxin that affects various tissue cell lines in vitro and inhibits bowel motility in vivo (3, 12). The genes encoding both toxins, tcdA and tcdB, have been sequenced, and both are known to disrupt the actin cytoskeleton of intestinal epithelial cells by modifying Rho family proteins. Toxin A has long been considered more important (19,20), but an increasing number of reports of colitis due to TcdA-negative but TcdB-positive strains have now been made (5, 35). Furthermore, other virulence factors have now been identified. Recently, an increase in the frequency and severity of C. difficile-associated colitis, which is associated with a new strain that produces binary toxin (actin-specific ADP-ribosyltransferase) and is resistant to fluoroquinolones in vitro, has refocused attention on early, accurate diagnosis (2,9,23,29,36).Cell culture cytotoxicity neutralization assays (CCNA), which detect ...

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Section: Discussionmentioning

confidence: 99%

Yield of Stool Culture with Isolate Toxin Testing versus a Two-Step Algorithm Including Stool Toxin Testing for Detection of Toxigenic Clostridium difficile

Reller¹,

Lema²,

et al. 2007

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“…The PPV of 21.4% for GDH alone confirmed the need to pursue additional testing of GDHpositive/toxin or PCR negative specimens to resolve these specimens as positive or negative for C. Difficile toxin. Zheng et al (26) reported that the Techlab C. diff Chek-60 GDH assay had good sensitivity compared to CYT testing of 92%, but it had a low specificity of 89.1% and poor positive predictive value (PPV) of 57.7%.…”

Section: Discussionmentioning

confidence: 99%

“…In addition to the increased sensitivity of the assay, GDH antigens appear both in toxigenic and non-toxigenic strains, allowing for the detection of both variants in patient samples. Upon the identification of antigen in stool samples using a GDH ELISA, the presence of C. difficile should be confirmed using an alternate method because it has low specificity despite its high sensitivity (12).…”

Section: Discussionmentioning

confidence: 99%

A Diagnostic Algorithm for the Detection of Clostridium difficile-Associated Diarrhea

Yoldaş¹,

Altındiş²,

Çufali³

et al. 2016

Balkan Med J

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Background: Clostridium difficile is a common cause of hospital-acquired diarrhea, which is usually associated with previous antibiotic use. The clinical manifestations of C. difficile infection (CDI) may range from mild diarrhea to fulminant colitis. Clostridium difficile should be considered in diarrhea cases with a history of antibiotic use within the last 8 weeks (community-associated CDI) or with a hospital stay of at least 3 days, regardless of the duration of antibiotic use (hospital-acquired CDI). Aims: This study investigated the frequency of CDI in diarrheic patients and evaluated the efficacy of the triple diagnostic algorithm that is proposed here for C. difficile detection. Study Design: Cross-sectional study. Methods: In this study, we compared three methods currently employed for C. difficile detection using 95 patient stool samples: an enzyme immunoassay (EIA) for toxin A/B (C. diff Toxin A+B; Diagnostic Automation Inc.; Calabasas, CA, USA), an EIA for glutamate dehydrogenase (GDH) (C. DIFF CHEK-60TM, TechLab Inc.; Blacksburg, VA, USA), and a polymerase chain reaction (PCR)-based assay (GeneXpert ® C. difficile; Cepheid, Sunnyvale, CA, USA) that detects C. difficile toxin genes and conventional methods as well. In this study, 50.5% of the patients were male, 50 patients were outpatients, 32 were from inpatient clinics and 13 patients were from the intensive care unit. Results:Of the 95 stool samples tested for GDH, 28 were positive. Six samples were positive by PCR, while nine samples were positive for toxin A/B. The hypervirulent strain NAP-1 and binary toxin was not detected. The rate of occurrence of toxigenic C. difficile was 5.1% in the samples. Cefaclor, ampicillin-sulbactam, ertapenem, and piperacillin-tazobactam were the most commonly used antibiotics by patients preceding the onset of diarrhea. Among the patients who were hospitalized in an intensive care unit for more than 7 days, 83.3% were positive for CDI by PCR screening. If the PCR test is accepted as the reference: C. difficile Toxin A/B ELISA sensitivity and specificity were 67% and 94%, respectively, and GDH sensitivity and specificity were 100% and 75%, respectively. Conclusion: Tests targeting C. difficile toxins are frequently applied for the purpose of diagnosing CDI in a clinical setting. However, changes in the temperature and reductant composition of the feces may affect toxin stability, potentially yielding false-negative test results. Therefore, employment of a GDH EIA, which has high sensitivity, as a screening test for the detection of toxigenic strains, may prevent false-negative results, and its adoption as part of a multistep diagnostic algorithm may increase accuracy in the diagnosis of CDIs.

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“…A positive result (optical density [OD] Ͼ 0.10) supported the detection of toxigenic C. difficile. Colonies on CCFA with typical characteristics of C. difficile (flat yellow colonies) were tested by PCR in an internally validated PCR assay targeting the putative toxin repressor gene tcdC (primers 5=-TCTAGCTAATTGGTCATAAG-3= and 5=-AATAGCAAATT GTCTGAT-3=) and the GDH "common-antigen" gene (gdh) using published primers (33). Despite variability in other regions of the PaLoc, the tcdC primers bind conserved regions in all toxigenic strains of C. difficile in GenBank (evaluated in August 2005) and over 1,200 sequenced strains in a recent survey (4).…”

Section: Methodsmentioning

confidence: 99%

Loop-Mediated Isothermal Amplification Compared to Real-Time PCR and Enzyme Immunoassay for Toxigenic Clostridium difficile Detection

et al. 2012

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dClostridium difficile infection is the primary cause of health care-associated diarrhea. While most laboratories have been using rapid antigen tests for detecting C. difficile toxins, they have poor sensitivity; newer molecular methods offer rapid results with high test sensitivity and specificity. This study was designed to compare the performances of two molecular assays (Meridian illumigene and BD GeneOhm) and two antigen assays (Wampole Quik Chek Complete and TechLab Tox A/B II) to detect toxigenic C. difficile. Fecal specimens from hospitalized patients (n ‫؍‬ 139) suspected of having C. difficile infection were tested by the four assays. Nine specimens were positive and 109 were negative by all four methods. After discrepant analysis by toxigenic culture (n ‫؍‬ 21), the total numbers of stool specimens classified as positive and negative for toxigenic C. difficile were 21 (15%) and 118 (85%), respectively. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were as follows: GeneOhm (95.2%, 100%, 100%, and 99.2%), illumigene (95.2%, 96.6%, 83.3%, and 99.2%), Tox A/B II (52.4%, 97.5%, 78.6%, and 92.4%), and Quik Chek Complete (47.6%, 100%, 100%, and 91.9%). The illumigene assay performed comparably to the GeneOhm assay with a slight decrease in test specificity; the sensitivities of both far exceeded those of the antigen assays. The clinical characteristics of the concordant and discrepant study patients were similar, including stool consistency and frequency. In the era of rapid molecular-based tests for toxigenic C. difficile, toxin enzyme immunoassays (EIAs) should no longer be considered the standard of care.

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Multicenter Evaluation of a New Screening Test That Detects Clostridium difficile in Fecal Specimens

Cited by 66 publications

References 24 publications

Yield of Stool Culture with Isolate Toxin Testing versus a Two-Step Algorithm Including Stool Toxin Testing for Detection of Toxigenic Clostridium difficile

Yield of Stool Culture with Isolate Toxin Testing versus a Two-Step Algorithm Including Stool Toxin Testing for Detection of Toxigenic Clostridium difficile

A Diagnostic Algorithm for the Detection of Clostridium difficile-Associated Diarrhea

Loop-Mediated Isothermal Amplification Compared to Real-Time PCR and Enzyme Immunoassay for Toxigenic Clostridium difficile Detection

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