An outbreak of Clostridium difficile infections due to new PCR ribotype 826

Objectives: To investigate an unusual outbreak of five patients with a total of eight episodes of a Clostridium difficile infection on a gastrointestinal surgical ward of a Dutch tertiary-care, university-affiliated hospital.
Methods: Clinical case investigations and laboratory analyses were performed. Laboratory analyses included PCR ribotyping, multiple-locus variable-number tandem repeat analysis typing, toxin typing, antimicrobial susceptibility testing and whole genome sequencing.
Results: The outbreak was associated with recurrent and severe disease in two of five patients. All episodes were due to a unique ribotype that was not recognized in the collection of an international network of reference laboratories and was assigned PCR ribotype 826. PCR ribotype 826 is a toxin A-, toxin B- and binary toxin-positive ribotype which according to molecular typing belongs to clade 5 and resembles the so-called hypervirulent ribotype 078. The presence of a clonal outbreak was confirmed by whole genome sequencing, yet the source of this newly identified ribotype remained unclear.
Conclusions: This newly identified C. difficile PCR ribotype 826 is part of clade 5 and might also have increased virulence. The recognition of this outbreak highlights the need for ongoing C. difficile infection surveillance to monitor new circulating ribotypes with assumed increased virulence.