Efforts to Control CDI Should Target All Virulent Strains Irrespective of PCR Ribotype

Infection with Clostridium difficile bacteria causes diarrhea and commonly occurs in hospitalized patients. This infection can be deadly, so knowing which patients are at highest risk is helpful. Researchers have found that infections caused by C. difficile bacteria containing genes for a specific toxin (binary toxin) are more likely to result in death. They do not yet know whether the toxin itself actually makes the bacteria more harmful or whether the gene is merely a red flag indicating that its carriers are more harmful. Regardless, knowing if this gene is present can help doctors treat patients accordingly to try to prevent more severe disease and death.

Sabrina Bacci, of the Department of Epidemiology at Statens Serum Institut Copenhagen in Denmark, and colleagues, compared 30-day case-fatality rates in patients infected with Clostridium difficile possessing genes for toxins A and B without binary toxin (n = 212) with rates in patients infected with C. difficile possessing genes for A, B, and binary toxin. The latter group comprised patients infected with strains of PCR ribotype 027 (CD027, n = 193) or non-027 (CD non-027, n = 72). Patients with binary toxin had higher case-fatality rates than patients without binary toxin, in univariate analysis (relative risk [RR] 1.8, 95% confidence interval [CI] 1.22.7) and multivariate analysis after adjustment for age, sex, and geographic region (RR 1.6, 95% CI 1.02.4). Similar case-fatality rates (27.8%, 28.0%) were observed in patients infected with CD027 or CD non-027. Binary toxin is either a marker for more virulent C. difficile strains or contributes directly to strain virulence.

The researchers say that efforts to control C. difficile infection should target all virulent strains irrespective of PCR ribotype.

Reference: Bacci S, et al. Binary Toxin and Death after Clostridium difficile Infection. Emerging Infectious Diseases, Vol. 17, No. 6. June 2011.