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C. difficile should be considered a Bacterial Priority Pathogen

Every few years, the World Health Organisation (WHO) puts out a list of Bacterial Priority Pathogens, which is intended “to guide research, development and strategies”. In reality, though, this list is also used by funding agencies to decide on research on which organism will be eligible for their resources. Great if your organisms makes the list, not so great if you don’t.

The 2024 list disappointingly did not include Clostridioides difficile. At the 8th International C. difficile Symposium (September 17-19, 2024) I took part in a panel discussion on this topic. Not surprisingly, the C. difficile field present there felt that the organism SHOULD have been on there. A WHO representative, having heard the panel discussion, indicated that if one wants to make the list, this requires effort from the community.

We took this to heart. Already at the meeting, I suggested we put together an Opinion piece to present the arguments why C. difficile is an organism that should be prioritized based on the WHO criteria. Together with the other panelists, we wrote a manuscript that was recently published in the journal Anaerobe.

We felt, however, that the message we wanted to convey went beyond the C. difficile field. After all, research on many organisms absent from the list could suffer consequences which ultimately impact patient safety. To highlight this, we prepared a Correspondence that is now published in Lancet Microbe, in response to a news item in that journal about the WHO list. I am particularly proud of the fact that - to highlight the fact that our message is broadly supported - we involved not only researchers and clinicians, but also patient/carer representatives and academic societies.

I hope that our efforts not only resound within the C. difficile community, but also act as a call-to-action for others to make sure that we continue with groundbreaking research to ultimately improve clinical care, whether or not “we made it on the list”.

 June 26, 2025
Wiep Klaas Smits