Peracetic acid-ethanol treatment of allogeneic avital bone tissue transplants--a reliable sterilization method

Based on the European Standard EN 1040, the validation guidelines of the German Federal Institute for Drugs and Medical Devices and CPMP guidelines we tested the antimicrobial effectiveness of a peracetic acid-ethanol sterilization procedure (PES) in allogenic avital bone transplants. Delipidated human bone spongiosa cubes (15 x 15 x 15 mm) served as tissue. Three enveloped viruses (human immunodeficiency virus type 2, pseudorabies virus, bovine virus diarrhoea virus) and three non-enveloped viruses (hepatitis A virus, poliovirus, porcine parvovirus) were used. The reduction of virus infectivity was measured as TCID50/ml in neutralized supernatants and bone homogenates. Staphylococcus aureus. Enterococcus faecium, Pseudomonas aeruginosa. Bacillus subtilis. Clostridium sporogenes, Mycobacterium terrae. Candida albicans, Aspergillus niger as well as spores of Bacillus subtilis were tested additionally. PES led to a reduction of virus titres by more than 4 log10. Only HAV showed a reduction below 4 log10 (2.87) with residual infectivity. After including a delipidating step for HAV-infected cells, a reduction of over 7 log10 HAV titre was found. For viable bacteria, fungi and spores a titre reduction below the detection level (5 log10) was achieved after an incubation time of 2 hours. The peracetic acid-ethanol procedure proved to be a reliable method for the sterilization of human bone transplants (layer thickness < or = 15 mm). However, additional safety measures (anamnestic informations, infectious serology, HIV-/HBV-/HCV-PCR in case of multiorgan donors) should be taken.