The aim of this study was to evaluate the effectiveness of a two-step algorithm for the detection of Clostridium difficile infection. Setting and Design: A two-step testing algorithm was evaluated for testing stool samples from patients suspected of Clostridium difficile infection (CDI). A total of 103 stool specimens were tested using the C. diff Quik Chek Complete enzyme immunoassay (EIA) test and the Xpert C. difficile PCR test. A two-step algorithm was implemented, and data from 3518 patient samples tested during a two-year period after implementation were analyzed to evaluate the effectiveness. The sensitivity, specificity, and positive and negative predictive values (PPV, NPV) of the Quik Chek Complete EIA test were calculated using the Xpert C. difficile PCR test as a reference method. The sensitivity, specificity, PPV, and NPV of the Quik Chek Complete EIA test for C. difficile toxin were 46.7%, 100%, 100%, and 91%, respectively. The two-step algorithm, which combined the Quik Chek Complete EIA with Xpert C. difficile PCR, improved the sensitivity and also provided rapid detection. When algorithm-based testing was performed daily, there was a 66% reduction in turnaround time compared to batch testing using a lengthy ELISA procedure. Postimplementation data analysis showed that almost 89% of the samples could be reported immediately by initial screening with Quik Chek Complete EIA. Only 11% of the samples gave discrepant results and required PCR confirmation. According to our results, the two-step algorithm is an effective tool for the rapid and reliable detection of toxigenic C. difficile from stool samples.
Introduction: Saudi Arabia has a moderate infection rate of tuberculosis (TB) in comparison to other countries in the region. The prevalence of TB varies among different parts of the Kingdom, with its western provinces reporting to have the leading rate of incidence. Method : In this retrospective study, Acid-fast bacilli smear (AFB), and nucleic acid amplification test (NAAT) were performed on all positive cultures from 254 identified TB cases from November 2006 to August 2016 in King Faisal Specialist Hospital and Research Center – Jeddah, Saudi Arabia. Results: From the positive cultures for Mycobacterium tuberculosis complex, 99.1% were found to be positive by using NAAT. From the NAAT positive samples, only 36.8% were positive for AFB. TB was predominant among the younger age group (59.4%) compared to the elderly population (35.8%) and pediatrics (4.7%), and it was also observed that males had a higher prevalence of 56.3 % in comparison to females. In regards to the site of infection, 53.1 % were pulmonary and 46.9% from an extrapulmonary. It was noted that resistance to first-line anti-TB drugs individually was found to be 11.0% to Streptomycin, 10.2% to isoniazid, 5.1% to pyrazinamide, 2.4% to Rifampicin, and 1.2% Ethambutol, yet multi-drug resistance (MDR) was found in 2.4% of observed cases. Conclusion: Young age predominance, low direct smear positivity, increased incidence of the extrapulmonary site of infection, and re-emergence of TB resistance all were observed in our study compared to previous national surveys.
Background Clostridium difficile-associated diarrhea (CDAD) is the commonest cause of nosocomial diarrhea. Methods for C.difficle detection include toxins or enzyme detection by immunoassays, cytotoxicity neutralization assay (CCNA) or FDA approved PCR. Due to the tedious and time consuming nature of the CCNA and the suboptimal specificity and sensitivity of EIAs, these assays cannot be used as stand-alone tests. One approach of combining these assays, is by two-step algorithm, where Ag-EIAs is used as screening test and confirmation of positives either by a toxin detection enzyme immunoassays or by CCNA. Another approach is a three-step algorithm, where Ag-EIAs is used as screening test, and all positives are tested by a toxin detection EIA and if toxin detection negative, further tested either by PCR or by CCNA. Therefore we aimed to evaluate a new two-step algorithm for the detection of toxigenic CD and its role in improvement of turn-around-time.MethodsA total of 3518 nonformed stool specimens from suspected cases of CDAD were collected. Specimens were tested either by GDH-toxin A/B ICA; or by GeneXpert C. diificile PCR as per the algorithm (Figure 1).ResultsOf 3518 stool specimens tested; 130 (3.70%) were positive and 2989 (84.96%) were negative by GDH-toxin A/B ICA while 399 (11.34%) required PCR. None of the negative GDH and positive toxin A/B samples tested positive by PCR. Also, none of the negative GDH and negative toxin A/B samples tested positive by PCR (Figure 2).ConclusionStudy indicates that when the GDH-toxin A/B ICA is used, almost 89 % of the results could be reported within 30 minutes; about 3.7 % of them being positive results and 84.96 % being negative. Confirmation of the discrepant GDH and Toxin A/B results was by PCR. The new algorithm offered rapid detection of C.difficile by ICA, judicious use of PCR and effectively reduced turnaround time.Figure-1:Two-step algorithm for C difficile testing.Figure-2:Results of two-step algorithm testing of 3518 stool samples for C difficile.Disclosures All authors: No reported disclosures.
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