Lab identification of Clostridum difficil – Essay Example

Antibiotics are common in altering the colonic flora, thus the correlation. Today, the infection has attained a global threat level, with deaths in large economies such as the United States estimated at above 14,000 per year. Diagnosis of Clostridium difficile is usually complicated since its outcomes are similar to those shown by other bacteria such as Campylobacter spp., Clostridium perfringens, or Salmonella spp. Several diagnostic methods exist, such as Colonoscopy, stool assays, and medical imaging, vary in their level of efficacy. This study will expound on the several diagnostic techniques of Clostridium difficile with regards to their effectiveness towards its assessment and treatment.
Several indicators may lead indicate that one has the Clostridium difficile infection.Lab identification of Clostridum difficil – Essay Example. Common symptoms include excessive recurrent dehydration, fever, tenderness in the lower abdomen, fever in some cases, general body discomfort (malaise), cramping abdominal pain, and diarrhoea that might be watery or in rare cases, bloody. Further suspicion might arise if these symptoms occur in patients who have received antibiotic treatment within three months’ time. Additionally, patients who are hospitalized also stand higher chances of contracting the Clostridium difficile infection. Finally, the diagnosis for the infection might be necessary if a hospitalized patient has recurring diarrhoea for about forty-eight hours. Although most of the mentioned cases are mostly within hospital settings, Clostridium difficile is also common away from medical centres.Lab identification of Clostridum difficil – Essay Example.
The risk of infection by Clostridium difficile depends on two factors; the exposure to the bacteria and exposure to antibiotics. The occurrence of Clostridium difficile is highest in infants, accounting for about 84.4%. Residents in long-term care facilities come second with about 57% occurrence, while occurrence in healthy adults accounts for about 5-15%.

We read with interest the paper by Swindells et al. on the evaluation of diagnostic tests for Clostridium difficile infection recently published in this journal (7). We welcome this medium-sized study, which is timely and provides some clarity to the performance of assays for this difficult diagnosis.

We note the excellent performance characteristics of the proposed two-step testing algorithm using C. Diff Quik Chek Complete to screen all diarrheal samples for the antigen glutamate dehydrogenase (GDH), followed by Xpert C. difficile PCR testing of any that are positive. Although the authors give us the performance characteristics of each of the tests individually, they do not give them for the algorithm as a whole. We have calculated these, together with receiver operating characteristic (ROC) curves, using the data provided in that paper. Compared to the stool cell cytotoxin neutralization assay (CCTN) as the reference, the two-step algorithm (using the Xpert as the confirmatory step) had a sensitivity of 100% (95% confidence interval [CI], 78% to 100%), a specificity of 97% (95% CI, 93% to 99%), and an area under the ROC (AU ROC) of 0.99 (95% CI, 0.97 to 1.00). This was statistically significantly better than the VIDAS enzyme immunoassay (EIA) for C. difficile toxins A and B, which had a sensitivity of 53% (95% CI, 27% to 79%), a specificity of 100% (95% CI, 97% to 100%), and an AU ROC of 0.77 (95% CI, 0.64 to 0.90) (Table 1; Fig. 1).

We note that all of the true-positive samples (as detected by CCTN) were positive for GDH and that no samples were EIA positive but GDH negative. This is in agreement with similar studies (1, 5).

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These findings are consistent with our own study, which used C Diff Quik Chek 60 for GDH as a screening test, followed by confirmation with BD GeneOhm PCR for C. difficile (3).Lab identification of Clostridum difficil – Essay Example.  This gave a sensitivity of 94% (95% CI, 80% to 99%), a specificity of 99% (95% CI, 98% to 99%), and an AU ROC of 0.97 (95% CI, 0.93 to 100) compared to toxigenic culture as the reference. This was also statistically significantly better than an EIA alone (Meridian Premier A/B EIA), which had a sensitivity of 39% (95% CI, 24% to 57%), a specificity of 99% (95% CI, 98% to 99%), and an AU ROC of 0.69 (95% CI, 0.61 to 0.77).

It is concerning that Swindells et al. found that the toxin component of the C. diff Quik Chek Complete assay was significantly more likely to detect ribotype 027 strains (which are generally thought to produce larger quantities of toxin), suggesting that this ribotype may be overestimated if a toxin EIA is relied upon for diagnosis. The prevalence of ribotype 027 is decreasing in the United Kingdom, and this certainly warrants more work (4).

It is possible that the toxin component of the C Diff Quik Chek Complete assay is redundant, since the GDH assay alone appears to have sufficient sensitivity and negative predictive value to be relied upon as an adequate screening test (1-3, 6, 8). Additionally, this may be less expensive to perform and has the advantage of being able to be processed by an automated machine using a spectrophotometer, so eliminating the subjectivity of interpretation by eye (which is required for the C Diff Quik Chek Complete assay). Swindells et al. found that the number of samples needing confirmatory PCR could be reduced from 22 to 11 if the GDH and toxin components of the C Diff Quik Chek Complete assay were both positive, and hence the sample was considered a true positive. Although based on a small number of samples, this algorithm has the potential to reduce financial costs and turnaround times. Further economic analysis is warranted. Lab identification of Clostridum difficil – Essay Example.

We do not believe that the currently available commercial toxin detection EIA kits are adequate for the laboratory diagnosis of C. difficile infection when used alone.

Direct detection of GDH in stool samples seems to be an accurate and rapid method to screen for the presence of C. difficile. Positive samples will need to be confirmed with a test that has a higher degree of specificity, but use of this test will reduce the number of more expensive and potentially difficult-to-perform confirmatory steps (approximately 20% of the samples needed a confirmatory step in our study). Lab identification of Clostridum difficil – Essay Example.