This retrospective study by Novosad et al.1 described Clostridioides difficile infection (CDI) antibiotic prescribing practices and adherence to the 2010 IDSA/SHEA CDI treatment recommendations2 using data from the Emerging Infections Program from 2013 to 2015. The investigators found that among the 18,243 CDI cases identified, metronidazole was the most commonly prescribed antibiotic (78%), following by vancomycin (42%), and fidaxomicin (2%). Of particular concern, guideline adherence for severe CDI was only 47%.

This multicenter study across 10 geographically diverse areas in the USA is one of the largest to investigate adherence to CDI guideline recommended therapy; however, the retrospective design and use of electronic health records is inherently subject to information bias, particularly for outpatients. Furthermore, more recent CDI practice guidelines3 have been published and adherence to new recommendations was not evaluated.

Despite these limitations, this study has important implications for clinical practice and future research. First, adherence to clinical practice guidelines has been previously associated with improved patient outcomes, including CDI attributable mortality and hospital length of stay4, 5; thus, non-adherence could potentially impact patient health. While this study identified potential factors affecting adherent prescribing, the specific reasons for non-adherence are unclear. It was particularly intriguing that hospital admission was most predictive of guideline adherence. This might reflect the use of standardized hospital treatment algorithms or more aggressive therapy in inpatients compared to outpatients. This might also reflect problems with outpatient provider education or access to care. Next, while the current study evaluated prescribing guideline adherence, patient adherence to the prescribed antibiotics could not be evaluated. The more recent CDI clinical practice guidelines recommend oral vancomycin or fidaxomicin as first-line therapy, regardless of severity. In the outpatient setting, these antibiotics can be cost-prohibitive compared to metronidazole, which might impact patient adherence, and ultimately risk for poor health outcomes (e.g., prolonged diarrhea or recurrent infection). To move the field forward, further studies are needed to assess implementation and adherence to the 2017 CDI treatment guidelines,3 but also to qualitatively evaluate specific reasons for prescribing and patient non-adherence, such that these barriers can be overcome in the future.