Time to update USMLE, ABEM, ABIM, and every other standardized test given in medicine – the old standby, metronidazole, has been downgraded for the treatment of Clostridium difficile infection.
This update from the Infectious Disease Society of America, published last month, refreshes clinical practice guidelines for C. diff. The article covers a few different topics, including the population to be tested, the criteria for diagnosis, and a whole host of management and prevention factors. As with any comprehensive guideline, there is the occasional discordance between the strength of the recommendation and the quality of the underlying evidence, so the generalizability of their recommendations may have limitations.
However, tucked into all the various nuances (which are all mostly worth looking over, of course), is one of the most profound changes – metronidazole has been demoted from first-line for C. diff infection. The co-first line agents are now oral vancomycin or oral fidaxomicin. The authors effectively cite the continued use of metronidazole as anachronistic dogma, with vancomycin repeatedly demonstrated as having greater effectiveness. Cure rates with oral vancomycin range from 80-97%, while metronidazole is a rung down at 70-84%. Unfortunately, the cost of oral vancomycin and fidaxomicin remains highly burdensome – leaving a role for metronidazole, but not preferred as before.
It should be noted virtually every author of the guideline has some sort of relationship with a pharmaceutical company, including the manufacturer of fidaxomicin. That said, oral vancomycin is generic – if still expensive – and has been around a long time.
“Clinical Practice Guidelines for Clostridium difficile Infection in Adults and Children: 2017 Update by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA)”
http://www.idsociety.org/Guidelines/Patient_Care/IDSA_Practice_Guidelines/Infections_By_Organ_System-81567/Gastrointestinal/Clostridium_difficile/