Despite the impressive burden of C difficile infection in the United States, it has become clear that there are many subtle complexities in diagnosis and classification of C difficile infection, which is also the case in oncology patients. Although toxigenic culture for C difficile is the gold-standard diagnostic technique, this method is infrequently performed because of its complex laboratory protocol requiring experienced technologists, delayed turnaround time for results, and limited scalability.

Nucleic acid amplification tests are highly sensitive but have correspondingly high rates of false-positive results.2 Even a test with 99% sensitivity and 99% specificity. The 2010 Infectious Diseases Society of America clinical practice guidelines for C difficile identified appropriate treatment of C difficile infection by severity category as a research gap for future study. In many centers, oncology care is delivered by specialized teams comprising nurses, providers, and pharmacists on dedicated units. Such organization of care affords important opportunities for antibiotic stewardship to reduce C difficile infection and infections with other multiple drug–resistant organisms

Unfortunately, there has been little update in the state of the literature on this topic since the release of these guidelines. Remaining questions about the clinical importance of severity classification and validation of these scores warrant further study.