Bacterial decontamination of blood stem cell apheresis products
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High-dose chemotherapy using autologous bone marrow or mobilized blood as the source of stem cells for haematologic rescue, is being widely used for a variety of haematological malignancies and solid tumours. To collect sufficient numbers of haematopoietic stem cells for successful engraftment, standard apheresis procedures are performed. Newer techniques and refinements of the procedure allow using only 1 to 2 apheresis products (AP) for autografting. Bacterial contamination of the AP, although very rare, sometimes occurs and may lead to generalized infection in the recipient. The apheresis must be repeated, sometimes even including time-consuming and costly mobilization. At our institution, the patients' blood stem cells are usually mobilized with chemotherapy followed by daily s.c. haematopoietic growth factor injections or with growth factor alone. An apheresis machine is used for collection through a central venous line and the AP is routinely checked for bacterial contamination. Results are only available after the product has been processed and cryopreserved. In the last 5 years, we observed bacterial contamination in four of our AP. Therefore, we investigated the possibility of in vitro antibiotic decontamination. Using standard antibiograms, we determined the sensitivities of the contaminating bacteria. By incubating the products with the specific antibiotics at bactericidal concentrations, we were able to sterilize the probes from the contaminating bacteria. In the concurrently performed controls without the active substance, bacteria were still detectable. We conclude that in selected cases, in vitro decontamination using pretested antibiotics, may be a feasible, cost-effective, and easy alternative to performing additional apheresis procedures.