title: Evaluation of a microbiological screening and acceptance procedure for cryopreserved skin allografts based on 14 day cultures.
abstract: Viable donor skin is still considered the gold standard for the temporary covering of burns. Since 1985, the Brussels military skin bank supplies cryopreserved viable cadaveric skin for therapeutic use. Unfortunately, viable skin can not be sterilised, which increases the risk of disease transmission. On the other hand, every effort should be made to ensure that the largest possible part of the donated skin is processed into high-performance grafts. Cryopreserved skin allografts that fail bacterial or fungal screening are reworked into 'sterile' non-viable glycerolised skin allografts. The transposition of the European Human Cell and Tissue Directives into Belgian Law has prompted us to install a pragmatic microbiological screening and acceptance procedure, which is based on 14 day enrichment broth cultures of finished product samples and treats the complex issues of 'acceptable bioburden' and 'absence of objectionable organisms'. In this paper we evaluate this procedure applied on 148 skin donations. An incubation time of 14 days allowed for the detection of an additional 16.9% (25/148) of contaminated skin compared to our classic 3 day incubation protocol and consequently increased the share of non-viable glycerolised skin with 8.4%. Importantly, 24% of these slow-growing microorganisms were considered to be potentially pathogenic. In addition, we raise the issue of 'representative sampling' of heterogeneously contaminated skin. In summary, we feel that our present microbiological testing and acceptance procedure assures adequate patient safety and skin availability. The question remains, however, whether the supposed increased safety of our skin grafts outweighs the reduced overall clinical performance and the increase in work load and costs.
authors.affiliation: Human Cell and Tissue Banks, Laboratory for Molecular and Cellular Technology, Burn Wound Centre, Queen Astrid Military Hospital, Brussels, Belgium. jean-paul.pirnay@mil.be
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Pirnay
authors.forename: Gunther
authors.initials: G
authors.lastname: Verween
authors.forename: Bruno
authors.initials: B
authors.lastname: Pascual
authors.forename: Gilbert
authors.initials: G
authors.lastname: Verbeken
authors.forename: Peter
authors.initials: P
authors.lastname: De Corte
authors.forename: Thomas
authors.initials: T
authors.lastname: Rose
authors.forename: Serge
authors.initials: S
authors.lastname: Jennes
authors.forename: Alain
authors.initials: A
authors.lastname: Vanderkelen
authors.forename: Miriam
authors.initials: M
authors.lastname: Marichal
authors.forename: Walter
authors.initials: W
authors.lastname: Heuninckx
authors.forename: Daniel
authors.initials: D
authors.lastname: De Vos
mesh_terms: D015925:Cryopreservation / Q000379:methods*; D003470:Culture Media; D003663:Decision Trees; D006801:Humans; D008403:Mass Screening / Q000379:methods*; D008828:Microbiological Techniques / Q000379:methods*; D012867:Skin / Q000382:microbiology*; D016038:Skin Transplantation / Q000379:methods*; D046509:Tissue Culture Techniques / Q000379:methods*; D014184:Transplantation, Homologous; D014186:Transportation
chemical_list: D003470:Culture Media