Origins of Staphylococcus epidermidis and Streptococcus oralis causing bacteraemia in a bone marrow transplant patient

Coagulase-negative staphylococcal bacteraemia in immunocompromised patients is often associated with the use of central venous catheters, while the pr oposed origin of viridans streptococci causing bacteraemia in this patient group is the oral cavity. This report describes an episode of polymicrobial bacteraemia caused by Staphylococcus epidermidis and Streptococcus oralis followed by several further episodes of S, epidermidis bacteraemia in a 15- year-old boy after bone marrow transplantation. Pulsed-field gel electropho resis (PFGE) of SmaI chromosomal DNA digests was used to compare blood cult ure and oral isolates of S, epidermidis and Str, oralis, The results indica ted that the mouth was the source of both S, epidermidis and Str, oralis ca using the first episode of bacteraemia, PFGE further demonstrated that the central venous catheter was the origin of a second strain of S, epidermidis responsible for subsequent episodes of staphylococcal bacteraemia, Both th e oral mucosa and central venous lines should be considered as potential so urces of organisms, including coagulase-negative staphylococci, associated with bacteraemia in immunocompromised patients.