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Bacterial contamination of autologous bone marrow during processing
D Smith1, S J Bradley, G M Scott
1Department of Haematology, University College London Hospitals, UK.
Abstract:
As part of an audit of the processing of autologous bone marrow, we found that marrow was often contaminated with organisms potentially pathogenic to neutropenic recipients. One of 14 marrows studied was found to be contaminated before the processing stage and five others became contaminated during processing. The organisms isolated at these stages were Propionibacterium sp., coagulase-negative staphylococci, Staphylococcus aureus and coryneforms, suggesting that the skin was the likely source of contamination. Five out of the 11 marrows returned to patients were found to be contaminated after thawing. Two of these were marrows previously shown to be contaminated with coagulase-negative staphylococci before freezing, and from these coagulase-negative staphylococci were isolated again, in one case the strains were indistinguishable. New organisms isolated after thawing included Bacillus sp. and Corynebacterium sporogenes suggesting contamination from the environment. No infections attributable to these organisms were demonstrated in any of the patients studied.
Insights
Autologous bone marrow processing can lead to microbial contamination, primarily from skin contact during collection and environmental sources post-thawing. While contamination was detected, no patient infections were linked to these organisms.
Area of Science:
- Microbiology
- Hematology
- Transplantation Science
Background:
- Autologous bone marrow transplantation is a critical therapy.
- Ensuring the sterility of processed bone marrow is vital for patient safety, especially for immunocompromised individuals.
Purpose of the Study:
- To audit the processing of autologous bone marrow for microbial contamination.
- To identify the sources and types of contaminating organisms.
- To assess the clinical relevance of detected contamination.
Main Methods:
- Audit of autologous bone marrow processing stages.
- Microbial culture and identification of organisms.
- Comparison of isolates before processing, during processing, and after thawing.
- Clinical review of patient outcomes.
Main Results:
- One of 14 marrows was contaminated pre-processing; five became contaminated during processing, likely from skin flora (Propionibacterium sp., coagulase-negative staphylococci, S. aureus, coryneforms).
- Five of 11 post-thaw marrows were contaminated, with some showing persistent coagulase-negative staphylococci and new environmental contaminants (Bacillus sp., Corynebacterium sporogenes).
- No infections were clinically attributed to the isolated microorganisms in the studied patients.
Conclusions:
- Autologous bone marrow processing presents risks of microbial contamination from both patient skin and the environment.
- Current processing methods may require enhanced aseptic techniques to minimize contamination.
- Despite detected contamination, clinical outcomes in this cohort were not adversely affected.