Author(s): Berry N, Sewell B, Jafri S, Puli C, Vagia S,
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Abstract AIM: To determine the clinical utility of a rapid molecular assay for Clostridium difficile infection (CDI) in an acute hospital setting. METHODS: From March to September 2011, stool specimens from inpatients in two acute hospitals with suspected CDI were tested prospectively by routine cell culture cytotoxin neutralization assay (CCNA), real-time polymerase chain reaction (PCR) using the GeneXpert (Cepheid Inc., Sunnyvale, CA, USA), and a dual testing algorithm [glutamate dehydrogenase (GDH)/toxin enzyme immuno-assay, Premier, Launch Diagnostics, Longfield, UK]. All patients with positive PCR, CCNA or discrepant results were reviewed by a multi-disciplinary team (treating clinician, gastroenterologist, microbiologist and infection control nurse). RESULTS: C. difficile detection rates were 11.7\% (PCR), 6\% (CCNA) and 13.8\% (GDH). Out of 1034 stool specimens included in the study, 974 (94.1\%) had concordant CCNA and PCR results. Eighty-nine percent (886/985) had concordant CCNA, PCR and GDH results, and 94.4\% (930/985) had concordant GDH and PCR results. Using clinical diagnosis as the reference, PCR had sensitivity of 99.1\%, specificity of 98.9\%, positive predictive value (PPV) of 91.9\% and negative predictive value (NPV) of 99.9\%. CCNA on a single sample had sensitivity of 51\%, specificity of 99.4\%, PPV of 91.9\% and NPV of 94.3\%. GDH had sensitivity of 83.8\%, specificity of 94.5\%, PPV of 64.7\% and NPV of 97.9\%. Almost twice as many patients were positive by PCR compared with CCNA (121 vs 62); 54/59 of those with discrepant results were clinically confirmed as CDI. CONCLUSION: Rapid diagnosis of CDI using PCR was timely, accurate and correlated well with clinical diagnosis. Copyright © 2014 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.
This article was published in J Hosp Infect
and referenced in Journal of Addiction Research & Therapy