Diphtheroids — Corynebacterium species other than C diphtheriae—are ubiquitous organisms and rarely pathogenic. When isolated in cultures of blood and other usually sterile body sites, diphtheroids are commonly dismissed as contaminants.1 In 1978, diphtheroids accounted for 3.2% of positive blood cultures and grew from 0.2% of all blood cultures (4,000) at the Montreal Children's Hospital (MCH).
A child, recently hospitalized at the MCH for evaluation of fever of unknown origin, was discharged without a diagnosis. The growth of diphtheroids in two of seven blood cultures was dismissed as unimportant because the child did not seem to be a compromised host and no apparent nidus of infection could be found. Subsequent events proved that these diphtheroids were the cause of his illness. The purpose of this report is to encourage the critical evaluation of all isolates from normally sterile sites such as blood, CSF, and bone marrow.