Guidelines to Implement Quality Management Systems in Microbiology Laboratories for Tissue Banking

Analysis of potential factors affecting allografts contamination at retrieval

The microbiological contamination of retrieved tissues has become a very important topic and it is a critical aspect in the safety of allografts, especially from multi-tissue donors whose tissues are frequently contaminated as a consequence of retrieval. We analysed a total of 10,107 tissues, 8178 musculoskeletal and 1929 cardiovascular tissues, retrieved from 978 multi-tissue donors. Of these, 159 heart-beating donors (HBD) were also organ donors, while the remaining 819 non-heart-beating donors (NHBD) were tissue donors only. A multivariate logistic model was used to determine the factors affecting contamination risk during retrieval. In the model, the dependent variable was the presence/absence of contamination while the covariates included were: gender, type of donor, age of donor, cause of death, previous skin donation, cadaver time, number of people attending the retrieval, number of tissues retrieved. Moreover, a second log-linear model was used to determine the number of strains isolated per tissue. Tissue contamination was statistically correlated with gender, type of donor, cadaver time, number of people attending the retrieval and season. In conclusion, to minimize the risk of bacterial contamination, aseptic techniques should be used at retrieval, with the number of retrieval team members kept to a minimum. In addition, cadaver time should be as short as possible and the donor should be refrigerated within a few hours after death.

Bacterial contamination of amniotic membrane in a tissue bank from Iran

Human Amniotic Membrane (AM) transplantation can promote tissue healing and reduce inflammation, tissue scarring and neovascularization. Homa Peyvand Tamin (HPT) tissue bank has focused on manufacturing human cell and tissue based products including AM. The purpose of this study is to evaluate and identify bacterial contamination of AMs that is produced by HPT for several ophthalmic applications. From July 2006 to April 2011, 122 placentas from cesarean sections were retrieved by HPT after obtaining informed consent from the donors. Besides testing donor's blood sample for viral markers, microbiological evaluation was performed pre and post processing. During tissue processing, decontamination was performed by an antibiotic cocktail including; Gentamicin, Ceftriaxone and Cloxacillin. Of 271 cesarean section AM donors who were screened as potential donors, 122 were accepted for processing and assessed for microbiological contamination. Donors' age were between 21 and 41 years (Mean = 27.61 ± 0.24). More than 92% of mothers were in their first or second gravidity with full term pregnancies. The most prevalent organisms were Staphylococci species (72.53%). After processing, contamination rates markedly decreased by 84.62% (p value = 0.013). According to our results, most of bacterial contaminations were related to donation process and the contamination pattern suggests procurement team as a source. Therefore we recommend that regular training programs should be implemented by tissue banks for procurement staff. These programs should focus on improved donor screening and proper aseptic technique for tissue retrieval. We also suggest that tissue banks should periodically check the rate and types of tissue contaminations. These data help them to find system faults and to update processing methods.