Bacterial contamination of autologous bone marrow: reinfusion of culture-positive grafts does not result in clinical sequelae during the posttransplantation course.

Objectives: Microbiological cultures and posttransplantation course were analyzed in order to investigate the incidence and clinical significance of bacterial contamination of autologous bone marrow (BM) grafts.

Methods: Cultures were obtained from BM after collection, BM concentrate after processing, contaminated/cryopreserved BM at thawing, and from peripheral blood (PB) following autologous BM transplantation (ABMT). The posttransplantation course of patients grafted with culture-positive BM was recorded and compared with patients who underwent ABMT with noncontaminated BM grafts.

Results: In 239 BM grafts processed, the incidence of microbiological contamination was 26.4% (n = 63). Fifty marrow grafts were contaminated by bacteria from the skin flora: coagulase-negative Staphylococcus (CNSC), Propionibacterium, and Corynebacterium species (79%). Thirty-eight patients underwent ABMT (day 0) with cryopreserved culture-positive BM, and 32 patients were evaluable for microbiological cultures at thawing: in 10 of 32 BM grafts CNSC was found prior to reinfusion. Following ABMT, PB cultures revealed CNSC in 5 of 38 patients between days +4 and +12. However, the late occurrence of positive PB cultures after BM reinfusion made a relationship between BM CNSC and PB CNSC unlikely. In 33 of 38 patients, no graft-contaminating bacteria were detected in PB. Comparison of the posttransplantation course of patients who received contaminated BM with that of patients grafted with noncontaminated BM showed no significant differences concerning time to engraftment, febrile days, and days on antibiotics.

Conclusion: (1) Collection and/or ex vivo processing can result in microbiological contamination of BM grafts predominantly with bacteria from the skin flora, and (2) only CNSC can be cultured at thawing from previously contaminated/cryopreserved BM. Since patients undergoing ABMT usually receive oral antibiotics from beginning of the conditioning regimen which are active against CNSC, no further administration of antibiotics is recommended for the reinfusion of bacterially contaminated BM grafts.