Double Blinded, Randomized Controlled Trial of Oral Vancomycin Versus Placebo in Hospitalized Patients With Diarrhea and Stool toXin NEGative But Nucleic Acid Amplification Test Positive for Toxigenic Clostridium Difficile (TOX NEG Trial)

Study Purpose:

The purpose of this study is to determine the risks and benefits of antibiotic treatment for Clostridium difficile infection (CDI) among patients whose stool samples are nucleic acid amplification test (NAAT) positive and enzyme immunoassay (EIA) negative for C. difficile.

Background:

Clostridium difficile infection (CDI) is the most common cause of healthcare-associated diarrhea. There is no gold standard diagnostic test for (CDI). Commercially available assays detect C. difficile or its toxins in stool. Nucleic acid amplification tests (NAAT) are much more sensitive than toxin enzyme immunoassays (EIA). However, clinical correlation is needed to determine who has CDI. Most US clinical microbiology laboratories have adopted NAATs for C. difficile under the presumption the enhanced analytical sensitivity was beneficial. Although some patients with NAAT-positive/toxin-negative stool have CDI and a false-negative toxin EIA, subsequent studies indicate most patients with NAAT-positive / toxin-negative stool do not have CDI. Rather, they are asymptomatic C. difficile carriers who have diarrhea for other reasons. Most of these studies also have limitations and considerable controversy remains for whether NAATs or toxin EIAs should be used when CDI is suspected.

Treatment of asymptomatic C. difficile carriers is not beneficial, and may result in harm. At hospitals that utilize NAATs, most patients with NAAT-positive / toxin-negative stool receive treatment for CDI. The most common treatments for CDI, metronidazole and oral vancomycin, are highly disruptive of the intestinal microbiome. These antimicrobials create selective pressures that promote the acquisition and proliferation of antimicrobial resistance and multidrug resistant organisms (MDRO), including public health threats such as MDRO Enterobacteriaceae like carbapenem-resistant Enterobacteriaceae (CRE) and extended-spectrum beta-lactamase (ESBL) producing organisms, vancomycin-resistant Enterococcus (VRE), and the latest emerging threat Candida auris. This leads to MDRO infections and MDRO spread to others. Paradoxically, unnecessary treatment for CDI may increase risk for CDI once treatment is stopped contributing to CDI-related adverse events and C. difficile spread to others. Unnecessary CDI treatment potentially harms both that patient and other people. Whether the benefit of treating patients with NAAT-positive/toxin-negative stool that are missed cases of CDI outweighs the risk of treating patients with NAAT-positive/toxin-negative stool that are asymptomatic C. difficile carriers remains unknown.