Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:1.4.1.2 (glutamate dehydrogenase)
4,380 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Faecal samples from 1007 patients suspected of having diarrhoea caused by Clostridium difficile infection are investigated for the presence of toxins A and B and for the presence of C. difficile-specific glutamate dehydrogenase (GDH). Toxigenic culture is performed on all samples and is used as the 'gold standard' for the purpose of the study. A marker for intestinal inflammation, faecal lactoferrin, is used on any samples that give a positive result in any of the above tests. Part of the study also involves an assessment of six commercial toxin kits to detect the presence of C. difficile toxins in faecal samples. This study revealed that the commercial toxin detection kits used can give rise to false-positive and false-negative results and that all demonstrated poor sensitivity when compared to the gold standard of toxigenic culture. Testing of faecal samples for GDH can be useful as a negative screening method as the results of this test show high correlation with culture. Faecal toxin testing can then be performed on all GDH-positive samples (GDH positivity is independent of toxigenicity in strains of C. difficile). The combined use of GDH and toxin testing, coupled with toxigenic culture, revealed that some patients with diarrhoea who harboured toxigenic strains of C. difficile were faecal toxin-negative. Lactoferrin appears to be a useful marker for the presence of inflammatory diarrhoea.
...
PMID:Laboratory diagnosis of clostridium difficile infection. An evaluation of tests for faecal toxin, glutamate dehydrogenase, lactoferrin and toxigenic culture in the diagnostic laboratory. 1934 18

Clostridium difficile infection (CDI) seems to be changing-with increasing virulence and incidence, more resistance to metronidazole, and worse outcomes. Accurate diagnosis is critical, but 3 common misconceptions lead to misdiagnosis: Clostridium difficile infection is a possibility when the patient has fewer than 3 loose stools per day; the glutamate dehydrogenase test for CDI is sensitive and thus is a good initial test; and repeating an insensitive laboratory test for CDI is useful. These misconceptions can lead to missed diagnoses (for example, when tests with low sensitivity are used) and to false diagnoses (for example, when tests are done in patients who are unlikely to have CDI because they have minimal diarrhea or negative results on recent tests). Diagnoses of CDI will be more accurate if clinicians use tests with a higher sensitivity, reduce the frequency of testing for a single episode of diarrhea, and give more attention to key elements of the patient's history.
...
PMID:Does my patient have Clostridium difficile infection? 1965 87

The continuing rise in the incidence of Clostridium difficile infection is a cause for concern, with implications for patients and health care systems. Laboratory diagnosis largely relies on rapid toxin detection kits, although assays detecting alternative targets, including glutamate dehydrogenase (GDH) and toxin genes, are now available. Six hundred routine diagnostic diarrheal samples were tested prospectively using nine commercial toxin detection assays, cytotoxin assay (CYT), and cytotoxigenic culture (CYTGC) and retrospectively using a GDH detection assay and PCR for the toxin B gene. The mean sensitivity and specificity for toxin detection assays were 82.8% (range, 66.7 to 91.7%) and 95.4% (range, 90.9 to 98.8%), respectively, in comparison with CYT and 75.0% (range, 60.0 to 86.4%) and 96.1% (91.4 to 99.4%), respectively, in comparison with CYTGC. The sensitivity and specificity of the GDH assay were 90.1% and 92.9%, respectively, compared to CYT and 87.6% and 94.3%, respectively, compared to CYTGC. The PCR assay had the highest sensitivity of all the tests in comparison with CYT (92.2%) and CYTGC (88.5%), and the specificities of the PCR assay were 94.0% and 95.4% compared to CYT and CYTGC, respectively. All kits had low positive predictive values (range, 48.6 to 86.8%) compared with CYT, assuming a positive sample prevalence of 10% (representing the hospital setting), which compromises the clinical utility of single tests for the laboratory diagnosis of C. difficile infection. The optimum rapid single test was PCR for toxin B gene, as this had the highest negative predictive value. Diagnostic algorithms that optimize test combinations for the laboratory diagnosis of C. difficile infection need to be defined.
...
PMID:Comparison of nine commercially available Clostridium difficile toxin detection assays, a real-time PCR assay for C. difficile tcdB, and a glutamate dehydrogenase detection assay to cytotoxin testing and cytotoxigenic culture methods. 1971 Feb 74

Current diagnosis of Clostridium difficile infection (CDI) relies upon detection of toxins A/B in stool by enzyme immunoassay [EIA(A/B)]. This strategy is unsatisfactory because it has a low sensitivity resulting in significant false negatives. We investigated the performance of a two-step algorithm for diagnosis of CDI using detection of glutamate dehydrogenase (GDH). GDH-positive samples were tested for C. difficile toxin B gene (tcdB) by polymerase chain reaction (PCR). The performance of the two-step protocol was compared with toxin detection by the Meridian Premier EIA kit in 500 consecutive stool samples from patients with suspected CDI. The reference standard among samples that were positive by either EIA(A/B) or GDH testing was culture cytotoxin neutralisation (culture/CTN). Thirty-six (7%) of 500 samples were identified as true positives by culture/CTN. EIA(A/B) identified 14 of the positive specimens with 22 false negatives and two false positives. The two-step protocol identified 34 of the positive samples with two false positives and two false negatives. EIA(A/B) had a sensitivity of 39%, specificity of 99%, positive predictive value of 88% and negative predictive value of 95%. The two-step algorithm performed better, with corresponding values of 94%, 99%, 94% and 99% respectively. Screening for GDH before confirmation of positives by PCR is cheaper than screening all specimens by PCR and is an effective method for routine use. Current EIA(A/B) tests for CDI are of inadequate sensitivity and should be replaced; however, this may result in apparent changes in CDI rates that would need to be explained in national surveillance statistics.
...
PMID:Two-step glutamate dehydrogenase antigen real-time polymerase chain reaction assay for detection of toxigenic Clostridium difficile. 2177 17

The incidence of Clostridium difficile infection (CDI) has risen almost 3-fold in the United States over the past decade, emphasizing the need for rapid and accurate tests for CDI. The Cepheid Xpert C. difficile assay is an integrated, closed, nucleic acid amplification system that automates sample preparation and real-time PCR detection of the toxin B gene (tcdB). A total of 432 stool specimens from symptomatic patients were tested by a glutamate dehydrogenase (GDH) assay, a toxin A and B enzyme immunoassay (EIA), the Xpert C. difficile assay, and a cell culture cytotoxicity neutralization assay (CCCN). The results of these methods, used individually and in combination, were compared to those of toxigenic culture. Results for the Xpert C. difficile assay alone showed a sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of 94.4, 96.3, 84.0, and 98.8%, while the EIA alone gave corresponding values of 58.3, 94.7, 68.9, and 91.9%, respectively. An algorithm using the GDH assay and the EIA (plus the CCCN if the EIA was negative) showed corresponding values of 83.1, 96.7, 83.1, and 96.1%. The Xpert C. difficile assay was statistically superior to the EIA (P, <0.001 by Fisher's exact test) and to the GDH-EIA-CCCN algorithm (P, 0.0363). Combining the GDH and Xpert C. difficile assays lowered both the sensitivity and the NPV of the Xpert assay. The GDH-EIA-CCCN procedure required, on average, 2 days to complete testing on GDH-positive results, while testing by the Xpert C. difficile assay was completed, on average, in less than 1 h. Xpert C. difficile testing yielded the highest sensitivity and NPV, in the least amount of time, of the individual- and multiple-test algorithms evaluated in this study.
...
PMID:Clostridium difficile testing in the clinical laboratory by use of multiple testing algorithms. 2007 52

Currently, the diagnosis of Clostridium difficile infection (CDI) relies on the detection of toxins A and B in faeces but the sensitivity of these tests has been questioned, particularly in advanced disease. In this context, additional methods to enhance the diagnosis of C. difficile have been investigated. In this study, 1007 faecal samples are tested using toxigenic culture, an immunoassay for toxins AB and the C. difficile-specific glutamate dehydrogenase (GDH) test. Samples positive by any of the above tests are evaluated for the presence of faecal lactoferrin as an indicator of intestinal inflammation. Patients with evidence of inflammation but with negative toxin AB tests are followed up to assess clinical outcome. The toxin AB test was positive in 35 samples (3.4%), while 121 (12%) samples were culture-positive, 87 (8.6%) of which were toxigenic. Glutamate dehydrogenase proved to be a sensitive and specific marker of C. difficile with a negative predictive value of 99.3% (95% CI: 0.98-1.00). Faecal lactoferrin was positive in 52/129 (40.3%) samples tested. A cohort of 15 patients with a negative faecal toxin AB and a positive lactoferrin test was C. difficile culture-positive with a toxigenic isolate; clinically, all had advanced CDI. All demonstrated faecal toxin between five and 41 days later on repeat testing. It is suggested that a two-step algorithm be used to include screening faecal samples for GDH, with positive samples tested for faecal toxin AB and lactoferrin. Patients who present with a negative faecal toxin AB test and a positive lactoferrin test were serially tested for faecal toxin AB every five to seven days until a diagnosis was established. More sensitive tests than enzyme-linked immunosorbent assay (ELISA) for the detection of faecal toxin, or the use of a rapid specific test for the presence of a toxigenic strain, must be considered in such patients.
...
PMID:Detection of Clostridium difficile infection: a suggested laboratory diagnostic algorithm. 2009 24

The diagnosis of Clostridium difficile infection continues to be a challenge for many clinical microbiology laboratories. A new lateral flow assay, the C.Diff Quik Chek Complete assay, which tests for the presence of both glutamate dehydrogenase (GDH) and C. difficile toxins A and B, was evaluated for its ability to diagnose C. difficile disease. The results of this assay were compared to those of both PCR and toxigenic culture. The results showed that this assay allows 88% of specimens to be accurately screened as either positive (both tests positive) or negative (both tests negative) for the presence of toxigenic C. difficile in less than 30 min and with minimal hands-on time. Use of a random-access PCR for the analysis of specimens with discrepant results (one test positive and the other negative) allows the easy, rapid, and highly sensitive (100%; 95% confidence interval [CI], 89.6 to 100%) and specific (99.6%; 95% CI, 97.3 to 99.9%) diagnosis of C. difficile disease. The use of this algorithm would save institutional costs, curtail unnecessary isolation days, reduce the nosocomial transmission of disease, and increase the quality of care for patients.
...
PMID:Evaluation of the C.Diff Quik Chek Complete Assay, a new glutamate dehydrogenase and A/B toxin combination lateral flow assay for use in rapid, simple diagnosis of clostridium difficile disease. 2066 2

A multicenter clinical trial assessed the performance of the Cepheid Xpert C. difficile assay on stool specimens collected from patients suspected of having Clostridium difficile infection (CDI). A total of 2,296 unformed stool specimens, collected from seven study sites, were tested by Xpert C. difficile enrichment culture followed by cell culture cytotoxicity testing of the isolates (i.e., toxigenic culture with enrichment) and the study sites' standard C. difficile test methods. The methods included enzyme immunoassay (EIA), direct cytotoxin testing, and two- and three-step algorithms using glutamate dehydrogenase (GDH) screening followed by either EIA or EIA and an in-house PCR assay. All C. difficile strains were typed by PCR-ribotyping. Compared to results for toxigenic culture with enrichment, the sensitivity, specificity, and positive and negative predictive values of the Xpert assay were 93.5, 94.0, 73.0, and 98.8%, respectively. The overall sensitivity of the EIAs compared to that of enrichment culture was 60.0%, and the sensitivity of combined GDH algorithms was 72.9%; both were significantly lower than that of Xpert C. difficile (P < 0.001 and P = 0.03, respectively). The sensitivity of the EIA was significantly lower than that of the Xpert C. difficile assay for detection of ribotypes 002, 027, and 106 (P < 0.0001, P < 0.0001, and P = 0.004, respectively, Fisher's exact test), and the sensitivity of GDH algorithms for ribotypes other than 027 was lower than that for Xpert C. difficile (P < 0.001). The Xpert C. difficile assay is a simple, rapid, and accurate method for detection of toxigenic C. difficile in unformed stool specimens and is minimally affected by strain type compared to EIA and GDH-based methods.
...
PMID:Impact of strain type on detection of toxigenic Clostridium difficile: comparison of molecular diagnostic and enzyme immunoassay approaches. 2070 76

Toxin enzyme immunoassays (EIAs) are inadequate for the diagnosis of Clostridium difficile infection (CDI) when used alone. In September 2010 we replaced toxin EIA with a two-step algorithm, testing first with glutamate dehydrogenase and confirming with polymerase chain reaction for toxin B gene. We compared this to the gold standard of toxigenic culture, observing a positive predictive value of 96% (laboratory prevalence of 4.7%). There was no deterioration in turnaround time but there was a decrease of 11% in repeat specimens sent from the same patients. The improved performance of the algorithm increased the laboratory positivity rate from 2.2% to 5.6%. This led to an increase in our Trust CDI rate reported under the Health Protection Agency's mandatory surveillance scheme. We investigated whether the change was due to increasing nosocomial transmission, environmental contamination or consumption of antimicrobials, but found no evidence of this. We conclude that it probably resulted from the change in testing algorithm. Although we have improved testing and enhanced patient safety, we are likely to be unfairly financially penalised because of our apparent (but not real) increase in CDI rates. Assessment of CDI rates should take testing methodology into account and national policies should be revised to reflect this.
...
PMID:Mandatory reporting and improvements in diagnosing Clostridium difficile infection: an incompatible dichotomy? 2180 45

Rapid detection kits for toxin A/B in feces are widely used as a diagnostic tool for Clostridium difficile infection (CDI). Their low sensitivity, however, has been considered a problem. In this study, we evaluated a new rapid diagnostic kit for simultaneous detection of the glutamate dehydrogenase (GDH) antigen and toxin A/B, C. DIFF QUIK CHEK COMPLETE. A total of 60 stool specimens from 60 patients with antibiotic-associated diarrhea were examined. Using C. difficile culture as the reference method, the GDH portion of this kit indicated a sensitivity, specificity, and negative predictive value of 100, 93.3, and 100%, respectively. The toxin A/B portion showed a sensitivity and specificity of 78.6 and 96.9%, respectively, compared to the culture results of toxin B-positive C. difficile (toxigenic culture). Of the 23 specimens that showed "dual positives" for GDH and toxin A/B, 22 were toxigenic culture positive, whereas C. difficile culture was negative in all the 28 specimens that showed "dual negatives" for GDH and toxin A/B. Of the nine "GDH-positive and toxin A/B-negative" specimens, six exhibited positive results by toxigenic culture. Results showing "dual positives" and "dual negatives" for GDH and toxin A/B can be reported as "true positive" and "true negative," respectively, whereas additional testing for confirmation, such as toxigenic culture, is required for specimens with discrepant results. Diagnostic algorithms, utilizing the simultaneous detection kit for GDH and toxin A/B as an initial screening test, may be useful for accurate and efficient diagnosis of CDI as well as the control of healthcare-associated infections.
...
PMID:Evaluation of a simultaneous detection kit for the glutamate dehydrogenase antigen and toxin A/B in feces for diagnosis of Clostridium difficile infection. 2172 61


1 2 3 4 5 Next >>

---