Microbial contamination of harvested bone marrow and peripheral blood

The incidence and clinical consequences of microbiological contamination of autologous bone marrow and peripheral blood progenitor cells are not well documented. We therefore retrospectively analysed our experience with bacterial or fungal contamination of harvested bone marrow and/or peripheral blood. From January 1987 to the end of January 1994, 499 patients were harvested or which 301 were transplanted. A total of 3910 specimens obtained during three stages in the processing were assessed for microbial contamination: (1) in the operating room immediately after harvesting (1662 bags) with 2.1% culture positivity, (2) after processing for cryopreservation (1039 bags) with a further 1.1% cultures positive, and (3) after thawing at the time of reinfusion (1209 bags) of which 2.2% were culture positive. There were no culture positive specimens obtained from any peripheral blood progenitor cell products. The vast majority of the 85 culture positive specimens obtained from marrow were skin flora (89%) and 35% of all positive harvest specimens remained positive following processing and freezing. At least 36% of culture positive specimens were thought to have arisen as a result of exogenous contamination of blood culture bottles. Potentially pathogenic enteric organisms were present in nine (0.2%) specimens and infusion of these organisms occurred in four cases. A further seven patients were reinfused with marrow culture positive for skin organisms. No adverse clinical sequelae were noted following infusion of any contaminated products. However, clinical decision making continues to be influenced by culture results and multistage microbial culture continues to be of value in the management of our marrow recipients.