Can we identify patients at high risk of recurrent Clostridium difficile infection?

Although most patients with Clostridium difficile infection (CDI) can be managed effectively with discontinuation of prescribed antibiotics and additional treatment with oral metronidazole or vancomycin, up to 25% experience disease recurrence, usually within 30 days of treatment. Failure to mount a systemic anti-toxin antibody response differentiates patients with CDI and recurrent CDI from symptomless carriers of toxinogenic C. difficile. The immunological senescence that accompanies ageing may lead to impaired immune responses to C. difficile and contribute to the significant association between advancing age and increased risk of CDI recurrence. Inadequate immunity may also explain why previous episodes of recurrence constitute a significant risk factor for further CDI recurrences. Other risk factors for recurrent CDI include concurrent use of antibiotics for non-C. difficile infections (which perpetuate the loss of colonization resistance), proton-pump inhibitors, and other gastric acid anti-secretory medications, prolonged hospitalization, and severe underlying illness (as reflected by a high Horn index score). Prominent risk factors have been examined to develop and validate a clinical prediction tool for recurrent CDI, with three factors (age >65 years, severe underlying disease (by the Horn index score), and continued use of antibiotics for non-CDI infections) being highly predictive of CDI recurrence. Such simple clinical prediction rules have the potential to identify patients at high risk of recurrent CDI, and can alert the treating physician to the need for prompt recognition, confirmatory diagnosis and treatment with regimens ideally designed to mitigate the risk of subsequent recurrences.