Resistance to extended-spectrum cephalosporins and mortality in patients with Citrobacter freundii bacteremia

Background: This study was performed to characterize the clinical features and to identify the risk factors for resistance to extended-spectrum cephalosporins (ESCs) and for mortality in patients with Citrobacter freundii bacteremia. Patients and Methods: 105 patients (aged greater than or equal to 15 years) with C freundii bacteremia in 1991-2000 were retrospectively analyzed. Results: Nosocomial acquisition was identified in 78.1% of the patients. Hepatic, biliary and pancreatic disease was the most common underlying disease (65.7%) and the biliary tract was the most common site of infection (50.5%). The overall resistance rate to ESCs was 59.0% and was significantly associated with hepatic, biliary and pancreatic disease, recent surgery and procedure, biliary drainage catheter and previous antibiotic therapy in univariate analysis. However, only previous antibiotic therapy with ESCs (OR = 5.0, 95% CI 1.6-15.7, p = 0.006) and recent surgery or procedure (OR = 3.1, 95% CI 1.1-8.4, p = 0.03) were strong, independent risk factors in multivariate analysis. Mortality directly related to C. freundii bacteremia was 21.9% and there was no difference between cases with resistance and susceptibility to ESCs (19.4% vs 25.6%; p = 0.45). Mortality was significantly associated with rapidly fatal or ultimately fatal underlying disease, a solid tumor, septic shock and polymicrobial bacteremia in univariate analysis. Among patients who had therapeutic surgical procedures, mortality was Lower (4.5%, p = 0.04). Multivariate analysis revealed rapidly or ultimately fatal disease, septic shock and polymicrobial bacteremia as independent prognostic factors. Conclusion: Biliary infection was the leading cause of C. freundii bacteremia. Previous antibiotic therapy, especially with ESCs, frequently predisposed for resistance to these antibiotics. However, resistance to ESCs was not associated with increased mortality.