Non-severe Clostridioides difficile Infection: Are the data adequate to give up metronidazole?

Clostridioides difficile infections (CDI) are typical antibiotic therapy associated complications. Notwithstanding the fact that the clinical picture of CDI may extend to the development of a toxic megacolon with potentially life-threatening sequelae, mild infectious forms associated with uncomplicated diarrhoea are by far the most prevalent and should also be treated according to clear clinical practice guidelines. However, there are currently conflicting international guidelines governing metronidazole-based treatment of mild infections. In light of this shortcoming, we performed a selective literature search of guidelines and clinical studies relating to the use of metronidazole for mild CDIs. The evaluation of randomised controlled trials demonstrates that, in statistical terms, vancomycin is significantly superior to metronidazole (NNT 16). When large cohort studies are included, this difference in effectiveness is reduced to 2,5 % (NNT 40). Inconsistent criteria for defining a mild CDI, different doses, applications and time intervals (e.g. additional IV administration of metronidazole) and the retrospective nature of some studies make it difficult to identify the influence of possible interference variables in this evaluation. Nevertheless, a mild CDI can be successfully treated with metronidazole; other recommendations, particularly those of American associations, should be evaluated critically. It is important to note that this therapy recommendation does not apply to patients with chronic inflammatory bowel diseases or other patients with pertinent comorbidities.