To assess Connecticut medical providers’ concordance (2018–2019) with the 2017 Clostridioides difficile infection (CDI) treatment update by the Infectious Disease Society of America (IDSA) and the Society for Healthcare Epidemiology of America (SHEA). The effect of guideline concordance on CDI recurrence risk was also assessed.

Prospective, population-based study.

New Haven County, Connecticut, from January 1, 2017, to December 31, 2019.

CDI incident case (no positive tests in the prior 8 weeks), not limited by care setting.

Using data from the Emerging Infections Program’s CDI surveillance, severity and concordance were defined. Presence of megacolon and/or ileus defined fulminant disease; absence defined nonsevere/severe disease. Using 2017 treatment as baseline, 2018–2019 concordance was defined as receiving the recommended first-line antibiotic (ie, vancomycin or fidaxomicin for adult patients, vancomycin or metronidazole for pediatric patients) for exactly 10 days. For all analyses, significance was P < .05.

Among 990 cases, concordance increased from 24.8% in 2018 to 37.0% in 2019. First-line antibiotic concordance increased from 61.2% in 2018 to 79.9% in 2019. Recurrence risk was significantly associated with patients aged ≥65 years and was highest for those aged 75–84 years, but this factor was not significantly associated with concordance.

From 2018 through 2019, CDI treatment in New Haven County increasingly was concordant with the 2017 treatment update but remained low in 2019. Although concordance with treatment guidelines did not affect recurrence risk, close attention should be paid by medical providers to patients aged ≥65 years, specifically those aged 75–84 years because they are at an increased risk for recurrence.