Autologous transplant: microbial contamination of hematopoietic stem cell products

Hematopoietic progenitor cells from peripheral blood (HPCPB) are commonly used for autologous and allogenic transplants in patients with most various onco-hematological diseases, and despite the utilization of sterile techniques during collection and processing of these products, bacterial contamination can occur. This study aimed to investigate the microbial contamination of HPCPB products. Microbial cultures of 837 HPCPB products between the year 2000 and 2009 were retrospectively analyzed to determine the incidence of culture positivity and identify the main organisms that cause contamination. The microbiological studies were performed with an automated system (BacT/Alert® bioMérieux Corporate). Thirty-six (4.3%) of 837 microbial cultures were contaminated. Coagulase-negative Staphylococcus was the most frequent bacteria isolated from HPCPB products (20 [56%] of the 36 positive microbial cultures). Considering the 36 contaminated samples, 22 HPCPB products were infused and 14 discarded. Pre-and post-infusion antibiotic therapy of the patients transfused with contaminated products was established based on the isolated microorganism and its antibiogram. Microbial contamination rate of HPCPB products was low. Clinically significant outcomes after infusion of contaminated HPCPB products were not observed.

Evaluación de la contaminación microbiológica en productos de células progenitoras hematopoyéticas. Experiencia de un laboratorio de procesamiento de CPH y Banco de Sangre de Cordón Umbilical / Microbiological evaluation in hematopoietic progenitor cell products. Experience from an HPC processing laboratory and Cord Blood Bank

Los productos de células progenitoras hematopoyéticas (CPH) representan una fuente potencial de infección en pacientes inmunosuprimidos que reciben infusión de CPH como parte de su tratamiento. La probabilidad de contaminación de cada producto difiere según la técnica de colecta y el procesamiento aplicado. En este trabajo hemos realizado un análisis retrospectivo de los resultados de cultivos microbiológicos de 1707 productos de CPH obtenidos de sus tres fuentes (médula ósea, sangre periférica y sangre de cordón umbilical) con el objetivo de determinar la proporción de unidades contaminadas. Además, fueron comparadas las distintas técnicas de colecta y las diferentes manipulaciones a las que fueron sometidos los productos. Por otro lado, se analizaron las posibles fuentes de contaminación según el microorganismo identificado y se evaluó la supervivencia de los mismos luego del descongelamiento. La prevalencia de productos de CPH con cultivos microbiológicos positivos reportados en este estudio (5,2%) se corresponde con lo descripto en la literatura. No encontramos diferencias significativas al comparar los productos según la fuente de la cual provenían las CPH. Tampoco hubo diferencias según los procedimientos aplicados a cada unidad. Los microorganismos aislados en los productos de CPH fueron los esperados de acuerdo a la fuente de la cual provenían las células. Pudo comprobarse que algunos de ellos son capaces de sobrevivir a los procesos de criopreservación y descongelamiento. La estricta adhesión a las normas de buenas prácticas de manufactura y buenas prácticas tisulares es un requisito para minimizar los riesgos de introducir microorganismos contaminantes. Disponer de un producto de CPH seguro es fundamental para el éxito de un trasplante.

Hematopoietic stem cell products (HSCP) represent a potential source of infection for immunosuprressed patients that receive HSCP infusion as part of their treatment. The probability of contamination of a HSCP product depends on the collection technique as well as the processing performed. In this work we have carried out a retrospective analysis of the results of 1707 microbiological cultures of HSCP products obtained from three different sources: bone marrow, peripheral blood and umbilical cord blood. We determined the proportion of HSCP units that were contaminated by microorganisms. Furthermore we compared the results obtained with different collection techniques and with the distinct manipulations that were used for processing. Moreover we analysed the possible sources of contamination related to the microorganisms identified and we evaluated the survival of them after thawing. The proportion of HSCP products with positive microbiological cultures obtained in this study (5,2%) correlates with that reported by other authors. We have not found significant differences between the results achieved with HSCP products from different sources. There were neither differences depending on the procedures applied. The isolated microorganisms from the HSCP products were the expected in accordance with the source of the cells. It could be demonstrated that some of them were capable of surviving the cryopreservation and thawing processes. Adherence to good manufacture practices and good tissue practices regulations is critical for minimizing the risks of introducing contaminant microorganisms. A safe HSCP product is essential for the success of a transplant.