The impact of 30-day antecedent antibiotic exposure on Clostridioidesdifficile ribotype patterns and the relationship with clinical outcomes: A single center study.

Background: Antibiotic exposure is a known risk factor for Clostridioides difficile infection (CDI) and recurrence and can lead to infection with specific C. difficile strains. In this study, we sought to explore the relationship between antecedent antibiotic exposure and C. difficile antimicrobial resistance, and the impact of resistance on clinical outcomes.
Methods: This was a single center retrospective study evaluating patients with CDI between 2011 and 2021. A logistic regression model was used to evaluate the relationship between antecedent antibiotics in the 30 days prior to CDI and resistance among isolates. In addition, an exploratory analysis using a cause-specific Cox proportional hazards model evaluated the association between resistance and a composite outcome of clinical failure, relapse at 30 days or CDI-related death.
Results: we analyzed one isolate from 510 patients; resistance was noted in 339 (66.5 %) of the isolates. Exposure to fluoroquinolones and macrolides was associated with 2.4 (95 % CI 1.4-4.4) and 4.7 (95 % CI 1.1-20.5) increased odds of having resistance compared to other antibiotic class exposure, respectively. There were 58 (17.0 %) patients in the resistance group who developed the composite outcome and 24 (14.2 %) patients who lacked resistance who developed the composite outcome (HR 1.32, 95 % CI 0.81-2.14).
Conclusion: These findings suggest that fluoroquinolone and macrolide exposure were significantly associated with isolating a resistant strain, but we did not find significant differences in clinical outcomes based on the presence of antimicrobial resistance.
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: DSR has research contracts at Tufts Medical Center from Prolacta, Summit Therapeutics, Seres Health and Merck. He is also a consultant to Prolacta and Merck. MA has grant funding from CARB-X. JC has research contracts at Tufts Medical Center from Merck and Kamada. All other authors do not have any conflicts of interest.
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