Validation of the ‘Marburg bone bank system’ for thermodisinfection of allogenic femoral head transplants using selected bacteria, fungi, and spores

Abstract

The Marburg Bone Bank System ‘Lobator sd-2’ is widely used to process human femoral heads removed during aseptic surgery by thermal disinfection. The inactivating capacity of the thermodisinfection system was validated in compliance with current standards using a newly developed femoral head model. The following micro-organisms, bacteria and fungi, taken from the American Type Culture Collection were investigated: Staphylococcus aureus, Staphyloccus epidermidis, Enterococcus faecium, Pseudomonas aeruginosa, Bacillus subtilis including spores , Clostridium sporogenes, Mycobacterium terrae, Candida albicans and Aspergillus niger spores. Highly enriched suspensions of these micro-organisms were applied to the centre of the femoral heads. The reduction in the number of micro-organisms was determined by counting the colony-forming units (cfu) before and after processing the spiked test device in the ‘Lobator sd-2’ system. Vegetative bacteria, fungi and fungal spores were completely inactivated (reduction factor ≥6 log 10). The numbers of B. subtilis and C. sporogenes spores, both known to be heat-resistant, were reduced by one to two orders of magnitude. These bacteria serve as a model for spore forming pathogens which are not relevant in femoral heads from living donors. By processing human femoral heads from living donors by thermal disinfection using the Marburg Bone Banking system, a high level of safety is achieved regarding clinically relevant pathogens. To further increase the safety of the thermally treated femoral heads, we recommend that the medical history and present state of the donor, as well as the necessary serological tests should be taken into account.