Correlation between Clostridium difficile Bacterial Load, Commercial Real-Time PCR Cycle Thresholds, and Results of Diagnostic Tests Based on Enzyme Immunoassay and Cell Culture Cytotoxicity Assay

Dionne, Léa-Laurence; Raymond, Frédéric; Corbeil, Jacques; Longtin, Jean; Gervais, Philippe; Longtin, Yves

doi:10.1128/jcm.01444-13

Cited by 67 publications

(56 citation statements)

References 30 publications

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“…The findings from this study are promising and are consistent with prior investigations (11,(13)(14)(15). However, this study has several limitations.…”

Section: Discussionsupporting

confidence: 81%

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Clostridium difficile PCR Cycle Threshold Predicts Free Toxin

et al. 2017

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There is no stand-alone Clostridium difficile diagnostic that can sensitively and rapidly detect fecal free toxins. We investigated the performance of the C. difficile PCR cycle threshold (C T ) for predicting free toxin status. Consecutive stool samples (n ϭ 312) positive for toxigenic C. difficile by the GeneXpert C. difficile/Epi tcdB PCR assay were tested with the rapid membrane C. Diff Quik Chek Complete immunoassay (RMEIA). RMEIA toxin-negative samples were tested with the cell cytotoxicity neutralization assay (CCNA) and tgcBIOMICS enzyme-linked immunosorbent assay (ELISA). Using RMEIA alone or in combination with CCNA and/or ELISA as the reference method, the accuracy of C T was measured at different C T cutoffs. Using RMEIA as the reference method, a C T cutoff of 26.35 detected toxin-positive samples with a sensitivity, specificity, positive predictive value, and negative predictive value of 96.0% (95% confidence interval [CI], 90.2% to 98.9%), 65.9% (95% CI, 59.0% to 72.2%), 57.4% (95% CI, 52.7% to 62%), and 97.1% (95% CI, 92.8% to 98.9), respectively. Inclusion of CCNA in the reference method improved C T specificity to 78.0% (95% CI, 70.7% to 84.2%). Intercartridge lot C T variability measured as the average coefficient of variation was 2.8% (95% CI, 1.2% to 3.2%). Standardizing the input stool volume did not improve C T toxin specificity. The median C T values were not significantly different between stool samples with Bristol scores of 5, 6, and 7, between pediatric and adult samples, or between presumptive 027 and non-027 strains. In addition to sensitively detecting toxigenic C. difficile in stool, on-demand PCR may also be used to accurately predict toxin-negative stool samples, thus providing additional results in PCR-positive stool samples to guide therapy.

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“…The findings from this study are promising and are consistent with prior investigations (11,(13)(14)(15). However, this study has several limitations.…”

Section: Discussionsupporting

confidence: 81%

“…Several studies have shown a correlation between C. difficile fecal free toxins and bacterial/genomic burden or PCR cycle threshold (C T ) in diarrheal stools (11,(13)(14)(15). Leslie and colleagues showed that at a cutoff of Ն5.1 log 10 DNA copies/ml, they could correctly classify Ն95% of toxin-positive and 70% of toxin-negative stool samples (15).…”

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confidence: 99%

Clostridium difficile PCR Cycle Threshold Predicts Free Toxin

et al. 2017

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“…Maybe. Higher sensitivity toxin assays will decrease the number of CDI cases "missed" by toxin tests and bring the analytical and clinical performance closer to that of the traditional cell cytotoxin neutralization assay (2,30,56,57). This should be a good thing.…”

Section: Will Increasing the Sensitivity Of Assays For C Difficile Tmentioning

confidence: 99%

“…GDH detection is sensitive for CDI because C. difficile vegetative cells express and secrete GDH extracellularly, and GDH may play a role in C. difficile colonization in vivo (29). As a result, most clinical samples with toxigenic C. difficile detectable by culture or NAATs are positive by GDH immunoassays, and virtually all samples with toxins detectable are positive for GDH (3,9,30). The occasional samples that are positive by NAATs but negative for GDH have a low concentration of C. difficile organisms and no toxins, suggesting that these are most likely C. difficile carriers or patients on treatment (30).…”

mentioning

confidence: 99%

“…As a result, most clinical samples with toxigenic C. difficile detectable by culture or NAATs are positive by GDH immunoassays, and virtually all samples with toxins detectable are positive for GDH (3,9,30). The occasional samples that are positive by NAATs but negative for GDH have a low concentration of C. difficile organisms and no toxins, suggesting that these are most likely C. difficile carriers or patients on treatment (30). Most laboratory comparisons find that GDH immunoassays are Ͼ90% sensitive for C. difficile, as confirmed by two meta-analyses; a few studies report slightly lower sensitivities in the range of 83.1 to 87.6% (3,9,26).…”

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confidence: 99%

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Point-Counterpoint: What Is the Optimal Approach for Detection of Clostridium difficile Infection?

2017

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INTRODUCTION In 2010, we published an initial Point-Counterpoint on the laboratory diagnosis of Clostridium difficile infection (CDI). At that time, nucleic acid amplification tests (NAATs) were just becoming commercially available, and the idea of algorithmic approaches to CDI was being explored. Now, there are numerous NAATs in the marketplace, and based on recent proficiency test surveys, they have become the predominant method used for CDI diagnosis in the United States. At the same time, there is a body of literature that suggests that NAATs lack clinical specificity and thus inflate CDI rates. Hospital administrators are taking note of institutional CDI rates because they are publicly reported. They have become an important metric impacting hospital safety ratings and value-based purchasing; hospitals may have millions of dollars of reimbursement at risk. In this Point-Counterpoint using a frequently asked question approach, Ferric Fang of the University of Washington, who has been a consistent advocate for a NAAT-only approach for CDI diagnosis, will discuss the value of a NAAT-only approach, while Christopher Polage of the University of California Davis and Mark Wilcox of Leeds University, Leeds, United Kingdom, each of whom has recently written important articles on the value of toxin detection in the diagnosis, will discuss the impact of toxin detection in CDI diagnosis.

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Performance of commercial PCR assays to detect toxigenic Clostridioides difficile in the feces of puppies

Anis

Barnart

Barnard

et al. 2021

Veterinary Medicine & Sci

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Clostridioides difficile is an important enteric pathogen that causes significant morbidity and mortality in humans. With community‐acquired infections on the rise, it is important to identify reservoirs of the pathogen. Companion animals can be asymptomatic carriers of C. difficile and may therefore represent a reservoir, but epidemiological studies of C. difficile within the pet‐owner unit are needed, along with validated methods to detect C. difficile in both people and animals. The goal of this study was to assess the performance of commercial qPCR assays and a multiplex PCR for C. difficile compared to toxigenic culture. These assays were tested on up to 103 fecal samples from puppies, a population in which the prevalence of C. difficile is the highest. The sensitivities, specificities, positive predictive values and negative predictive values were respectively 84.2%, 87.7%, 61.5%, and 95.9% for the Cepheid GeneXpert; 66.7%, 66.7%, 29.6%, and 90.9% for the DiaSorin Simplexa; and 94.4%, 85.0%, 65.4%, and 98.1%, for the multiplex qPCR. The agreement was highest between the GeneXpert and the multiplex PCR (90.1% agreement, with a kappa statistic of 0.77). For diagnostic purposes, the positive predictive values of the assays were low. However, the high sensitivities of the assays could render them useful for epidemiologic purposes.

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Correlation between Clostridium difficile Bacterial Load, Commercial Real-Time PCR Cycle Thresholds, and Results of Diagnostic Tests Based on Enzyme Immunoassay and Cell Culture Cytotoxicity Assay

Cited by 67 publications

References 30 publications

Clostridium difficile PCR Cycle Threshold Predicts Free Toxin

Clostridium difficile PCR Cycle Threshold Predicts Free Toxin

Point-Counterpoint: What Is the Optimal Approach for Detection of Clostridium difficile Infection?

Performance of commercial PCR assays to detect toxigenic Clostridioides difficile in the feces of puppies

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