June 15, 2017
2 min read

Study findings challenge recommendations for defining recurrent CDI, reinfection

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Researchers have suggested that extending the currently recommended 8-week cutoff period that distinguishes recurrent Clostridium difficile infection, or CDI, from reinfection with a new strain may provide a more accurate classification of CDI events.

According to Ana Durovic, MD, of the Division of Infectious Diseases and Hospital Epidemiology at the University Hospital Basel, Switzerland, and colleagues, both the European Centers for Disease Control and Prevention (ECDC) and the National Healthcare Safety Network define recurrent CDI as a case occurring within 8 weeks of a previous CDI episode. However, the accuracy of the 8-week cutoff period in distinguishing recurrent CDI from reinfection has not been previously validated.

The researchers assessed the utility of the 8-week cutoff period in a cohort of patients with either recurrent CDI or reinfection, based on standard definitions, who were treated at the University Hospital Basel from January 2004 to December 2013.

Among 106 patients with strains available from both CDI events, 36 of 47 patients with recurrence and 27 of 59 with reinfection had identical strains. The researchers estimated that the standard definition of recurrent CDI vs. reinfection was associated with 56% sensitivity, 74% specificity, 53% negative predictive values and 76% positive predictive values. They assessed whether there were additional clinical variables that may be used to help distinguish CDI events. Although patients with reinfection were more likely to be older and less likely to receive steroids 8 weeks after the initial diagnosis than patients with recurrent infection, only time following initial diagnosis remained significantly associated with reinfection (OR = 1.27; 95% CI, 1.05-1.53) in a multivariate analysis.

“Our results are supported by previous studies revealing that 65% of all second episodes of CDI occurring between 8 weeks and 11 months after the initial diagnosis were caused by identical strains, and identical strains were identified in recurrent CDI up to 26 weeks after initial diagnosis,” they wrote. “Similarly, an earlier study performed on a smaller cohort of HIV patients revealed that recurrent CDI was caused by the same strain of C. difficile after more than 8 weeks in a relevant proportion of patients. However, these studies did not investigate other time frames.”

Durovic and colleagues determined that an extended cutoff period of 20 weeks resulted in the best match for sensitivity (83%) and specificity (58%). However, they concluded that their findings warrant further validation in additional studies.


“Because identification of identical strains of C. difficile during both episodes of CDI may indicate treatment failure, and while identification of different strains rather reflects ongoing exposure to risk factors and possibly longer time to reconstitution of gut flora, this distinction is critical when studying treatment effects,” they wrote.

“Furthermore, correct classification of CDI events is important regarding accurate reporting of infection rates attributed to health care institutions as mandated in the United States for hospitals participating in the Centers for Medicare and Medicaid Service (CMS) Input Prospective Payment System Quality Reporting Program and recommended in Europe by public health authorities such as the ECDC.” – by Stephanie Viguers

Disclosure: Durovic reports no relevant financial disclosures. Please see the full study for a list of all other authors’ financial disclosures.