| Popis: |
New rapid methods for the diagnosis of CDI are constantly being developed. One of these, the Oxoid toxin A test (Unipath, Basingstoke, Hampshire, UK), was evaluated by comparison with a cytopathic effect (CPE) method, using 100 strains of C. difficile. The performance of the Oxoid toxin A test was only as good as the CPE method read at 6 hours, with a sensitivity of 725 and a specificity of 94%. This is not likely to be sufficiently accurate to be relied on as a single test for CDI. Furthermore, with the advent of disease caused by toxin A negative / toxin B positive strains, toxin A tests are no longer to be recommended for CDI diagnosis. The epidemiology of CDI was studied in two ways. 1) The prevalence of C. difficile toxin A negative / toxin B positive strains was measured in 269 isolates from symptomatic hospital patients in Leeds and Bradford, using toxin gene detection PCR. 2) A comparison of C. difficile strain type was made between isolates from symptomatic community patients in Leeds and Truro, using ribo-spacer (RS) PCR. There were 15 isolates from Leeds and 39 from Truro. The epidemiological investigation indicated that there were no toxin A negative / toxin B positive strains apparent in Leeds or Bradford, although these strains have been reported from other areas of the country. Amongst Leeds community patients, 60% of strains isolated were identical to the 'endemic' hospital strain (which accounts for over 80% of sporadic CDI cases in Leeds hospital patients). By contrast, this strain was not present in the Truro population (p= C. difficile colonisation between the two groups. The odds ratio (OR) for CDI in CTX treated patients compared with those who received PT was 14.6 (CI = 1.7-124.7). The number needed to treat (NNT) to save one case of CDI was 2.18. |
