Swab or biopsy samples for bioburden testing of allograft musculoskeletal tissue?

Bacterial contamination of bone allografts in the tissue banks: a systematic review and meta-analysis

BACKGROUND

Bone allografts are harvested and transplanted under sterile conditions. However, the risk of bacterial contamination of grafts during these processes is a health concern. Bioburden testing and bacterial contamination detection are conducted to ensure allograft sterility.

AIM

The present study aimed to determine the incidence of bacterial contamination in bone allografts based on different classifications.

METHODS

PROSPERO registration number was received for the study. Systematic searches were conducted in PubMed and EMBASE databases with relevant keywords from January 2000 to March 2021. After choosing related studies according to the PRISMA flow diagram, Stata software was used for data analysis. We considered I² ˃ 50% as heterogeneity between studies.

FINDINGS

The overall incidence of bacterial contamination was 12.6% (95% CI 0.100, 0.152) among 19,805 bone allografts of 17 studies. The bacterial contamination rate among bone allografts was 10.8% before 2010 and 14.7% in 2010-March 2021. The contamination frequency in Asia, Europe, and Australia was 11.5%, 14.3%, and 5.2%, respectively. Bone contamination rates were higher in cadaver donors (19.9%), retrieval time sampling (13.5%), and swab samples (13.2%) compared to those in living donors (7.5%), implantation time sampling (6.9%), and bone fragments cultures (6.3%). Bacterial contamination was recovered 24.4%, 19.7%, 13.2%, and 21% from tibia, fibula, femoral, and other bones, respectively. Staphylococcus spp. was the predominant isolated bacteria from bones (63.2% of all isolated genera), followed by Propionibacterium spp. (10.6%).

CONCLUSION

The high contamination of bone allografts is a health concern, indicating the need for more health monitoring and improvement of standards.

The BD BACTEC FX blood culture system with the gentlemacs dissociator is suitable for sterility testing of heart valve and vascular allografts-A validation study

To present our validation study of the BD BACTEC FX blood culture system for sterility testing of cardiovascular tissues aimed for human application. For operational qualification, we performed temperature mapping of the system, vacuum test using non-inoculated BACTEC vials, and growth promotion tests by injecting contaminant strains into aerobic and anaerobic bottles. For performance qualification, negative control, assessment of method suitability, evaluation of sensitivity limits, control of neutralization of antibiotics in biopsy samples from allografts and tissue toxicity effects, were performed. Tissue samples and transport/cryopreservation solutions were homogenized in GentleMACS Dissociator and injected into BACTEC Plus aerobic and anaerobic vials for incubation at 35 °C for 14 days. Tissues were spiked with aerobic and anaerobic bacteria and fungi. Growth of contaminants appeared in all aerobic and anaerobic vials for Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa; in anaerobic vials for Cutibacterium (Propionibacterium) acnes and Clostridium sporogenes; and only in aerobic vials for Candida albicans and Aspergillus brasiliensis. The majority of bacterial strains were detected within two days (59-100%), exceptionally between 3 and 14 days. In contrast, fungal contaminations were detected within 2, 3-6, 7-10 and after 10 days of incubation in 33.3, 71.6, 96.6 and 99.9% of cases,respectively. Uninhibited growth appeared in the tissue biopsies and homogenized tissues with and without antibiotics and in other solutions. BD BACTEC blood culture system with GentleMACS Dissociator is a rapid and efficient tool for detection of contamination in cardio-vascular tissues aimed for human application.