Differences in the rate of carbapenem-resistant Enterobacteriaceae colonisation or Clostridium difficile infection following frontline treatment with tigecycline vs. meropenem for intra-abdominal infections

Objectives: We hypothesised that treatment with a tigecycline-based antimicrobial regimen for intra–abdominal infection (IAI) could be associated with lower rates of subsequent carbapenem-resistant Enterobacteriaceae (CRE) colonisation or Clostridium difficile infection (CDI) compared with a meropenem-based regimen. Methods: We performed a retrospective, single-centre, matched (1:1) cohort analysis of all patients who received at least 5 days of empirical or targeted tigecycline (TIG)- or meropenem (MER)-based treatment regimens for IAI over a 50-month period. Patients with previous CRE colonisation and CDI were excluded. Risk factors for CRE and CDI were assessed with a Cox regression model that included treatment duration as a time-dependent variable. Thirty-day mortality was assessed with Kaplan-Meier curves. Results: We identified 168 TIG-treated and 168 MER-treated patients. The cumulative incidence rate ratio of CDI was 10-fold lower in TIG-treated vs. MER-treated patients (incidence rate ratio [IRR] 0.10/1000 patient-days, 95%CI 0.002–0.72, P = 0.007), but similar incidence rates were found for CRE colonisation (IRR 1.39/1000 patient-days, 95%CI 0.68–2.78, P = 0.36). In a multivariate Cox regression model, the receipt of a TIG- vs. MER-based regimen was associated with significantly lower rates of CDI (HR 0.07, 95%CI 0.03–0.71, P = 0.02), but not CRE (HR 1.12, 95% CI 0.45–2.83, P = 0.80). All-cause 30-day mortality was similar in the two groups (P = 0.46). Conclusion: TIG-based regimens for IAI were associated with a 10-fold lower incidence of CDI compared with MER-based regimens, but there was no difference in the incidence of CRE colonisation.