Bacteraemia from an unrecognized source (occult bacteraemia) occurring during Clostridium difficile infection.

Background: The purpose of this investigation was to determine if disruption of the colonic epithelium during Clostridium difficile infection (CDI) is associated with bacteraemia due to secondary bacterial invasion by enteric organisms.

Methods: We reviewed the medical records of 505 randomly selected individuals from a database of patients who tested positive for C. difficile toxin and identified bacteraemias that occurred in 2 periods-the pre-CDI and post-CDI periods. Medical records were reviewed to determine a source for each case of bacteraemia. Staphylococcal bacteraemias were excluded from the analysis.

Results: In the pre-CDI period, 28 of 505 (5.5%) patients had non-staphylococcal bacteraemia. A focus of infection was found in 24 of 28 (85.7%) cases. During CDI, 30 of 505 (5.9%) patients had non-staphylococcal bacteraemia; in the majority (19 cases, 63.3%) a focus of infection was not identified (p < 0.001). In the pre-CDI period, 16 of 28 (57.1%) blood cultures yielded Gram-negative pathogens compared to 9 of 30 (30%) in the CDI period (p = 0.04). Seven of 28 (25%) blood cultures in the pre-CDI period yielded enterococci compared to 15 of 30 (50%) in the CDI period (p = 0.05).

Conclusions: The incidence of non-staphylococcal bacteraemias in the pre- and post-CDI periods was nearly the same. Cases of bacteraemias in the CDI period more frequently involved organisms of unknown source and uncertain pathogenicity, and were usually not found to require antimicrobial therapy. The data favour the assumption that CDI-associated bacteraemia may be associated with bacterial invasion of the damaged colonic epithelium.