Diagnostic utilities of a fully automated molecular test for toxigenic Clostridium difficile.

Laboratory underdiagnosis of toxigenic Clostridium difficile can lead to inappropriate management of C. difficile infection (CDI). A fully automated molecular test (FAMT), BD MAX, and enzyme immunoassays for C. difficile glutamate dehydrogenase (GDH) and for toxin A/B antigen test were evaluated using clinical specimens. Laboratory analysis of 231 fecal specimens from patients suspected with CDI, indicated that the sensitivity (Sn), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) of FAMT was 98.1%, 98.9%, 96.3%, and 99.4%, while that of toxin A/B antigen was 52.8%, 100.0%, 100.0%, and 87.7%, respectively, compared to toxigenic culture. Sn, Sp, PPV, and NPV of GDH test compared to toxigenic culture was 92.5%, 94.4%, 83.1%, and 97.7%, respectively. FAMT can support the accurate laboratory diagnosis of toxigenic C. difficile and be an effective tool for appropriate treatment of CDI.

Evaluation of a simultaneous detection kit for the glutamate dehydrogenase antigen and toxin A/B in feces for diagnosis of Clostridium difficile infection.

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.

[Usefulness of immunological detection of both toxin A and toxin B in stool samples for rapid diagnosis of Clostridium difficile-associated diarrhea].

Toxin detection from stool specimens is critical for the diagnosis of Clostridium difficile-associated diarrhea (CDAD). In Japan, only two toxin detection kits targeting toxin A alone are commercially available. We evaluated ImmunoCard Toxin A & B (ImmunoCard), based on enzyme immunoassay for the rapid detection of both C. difficile toxins A and B in stool specimens, compared to a toxin A detection kit (Uniquick) and cytotoxin assay. C. difficile was also cultured from stool specimens and the toxin production type of C. difficile isolates was identified by PCR analysis. Compared to cytotoxin assay, ImmunoCard sensitivity was 86.2%, specificity 93.8%, positive predictive value 91.8%, and negative predictive value 89.4% (n = 146). Sensitivity was significantly higher than that of Uniquick (60.0%, p = 0.0016). ImmunoCard detected 90.6% of cytotoxin positive specimens with isolated toxin A-positive, toxin B-positive C. difficile strains (Uniquick; 67.9%, p = 0.008) and 70.0% of these with isolated toxin A-negative, toxin B-positive C. difficile strains. Although ImmunoCard was slightly less sensitive than cytotoxin assay, it requires no special equipment and completes the entire test in up to 20 min. ImmunoCard thus appears very useful in the rapid diagnosis of CDAD in the clinical laboratory. Kits for the detection of both C. difficile toxins A and B should be immediately introduced into Japan to ensure the correct diagnosis of CDAD and infection control.

[Control of hospital infection of influenza: administration of neuraminidase inhibitor and cohort isolation of influenza patients].

Influenza can spread rapidly to patients and staff in hospitals when influenza is introduced by visitors, staff, or patients. In order to prevent and control outbreaks of influenza in hospitals, systematic management is important. This consists of a rapid diagnostic test, cohort isolation and administration of neuraminidase inhibitor. In the 2002-2003 season, 53 elderly patients were admitted to our hospital under the control of the system. The mean age was 78.8 years. We set 2 isolation rooms (10 beds) for influenza patients. Patients were isolated in the room for three days, administered oseltamivir immediately. Oral oseltamivir was well tolerated. Mean hospital stay was 10.7 days. 36 cases developed complications requiring antibiotics, and one patient developed a catheter related infection. Under the system, we could avoid cross infection of influenza. In two cases, nose swabs were taken for virus isolation every 12 hours and a rapid decline in virus shedding was observed after treatment.

[An epidemic of rotavirus infection in a nursing home for the elderly in Japan].

An outbreak of diarrheal disease in a Japanese home for aged is reported. Out of 202 residents, 47 cases complained of diarrhea (23.3%) during a month. Clinical symptom were diarrhea (100%) vomiting (40.4%) and fever (31.9%). Fecal examination of 9 cases revealed positive A-group rotavirus antigen. Bacterial and small round shaped virus infection was excluded. Examination of rotavirus antibody, CF titer was positive in about 50% in each age group but the titer decreased year by year. In Japan, rotavirus infection has been epidemic only in nursing home for baby and titer of antigen has been believed to be sustain by repeated provocation. However, Japanese situation is changing to be west Europe and north America.