Epidemiology and Outcomes of Clostridial Bacteremia at a Tertiary-Care Institution

Clostridial bacteremia (CB) is a rare clinical entity, accounting for less than 2-3% of all blood cultures. CB is frequently associated with intra-abdominal infections and underlying malignancy, particularly colon cancer or leukemia. Clostridium species are commonly isolated from blood cultures as a part of polymicrobial bacteremia. The mortality rate among patients with CB has been reported to be as high as 50%. The presentation and outcome of CB depends on underlying host defenses and the type of Clostridium species causing infection. A favorable outcome for CB appears to depend on the prompt initiation of appropriate antibiotics and surgical intervention. All patients with positive blood cultures for Clostridium species, from January 1995 to December 2003, were included in this study. Medical records of these patients were reviewed for age, sex, underlying diseases (such as malignancy and diabetes), antibiotic use, and outcome. Antimicrobial therapy was defined as either “appropriate” or “insufficient” based on its activity against Clostridium species. In-hospital, postdiagnosis survival was examined by Kaplan-Meier methodology and comparisons made by the Mantel-Cox Log-Rank test. Ninety-two percent of the patients had monomicrobial CB. C. perfringens was the most frequently isolated pathogen, seen in 60% of cases. The most common underlying conditions were genitourinary and gastrointestinal malignancies, and diabetes. The overall mortality was 48%. Patients with malignancy had a significantly higher 2-day mortality rate (54%) compared to patients without malignancy (8%, p = 0.023). The mortality rates varied according to type of Clostridium species. Patients with C. innocuum bacteremia had a significantly higher 2-day mortality rate (100%) compared to patients with C. septicum (67%), and to patients with C. perfringens (27%) (p = 0.004). “appropriate” antibiotics were given to 64% of the patients, 16% were on antibiotics with “insufficient” coverage, and 20% were not given any antibiotics. Patients receiving “insufficient” antibiotic therapy had a significantly higher 2-day mortality rate (75%) compared to patients on “appropriate” antibiotics for Clostridium (12.5%) (p = 0.011). CB is associated with high and rapid mortality, especially in patients with malignancy. Early mortality was significantly lower in patients receiving antibiotics with adequate coverage for Clostridium species.