To the Editor—To assess the contamination rate of retrieved bone allografts and the infection rate after bone allotransplantation, we performed the retrospective review of 2 audits to evaluate the quality of bone bank activities in the University hospital in Central Serbia using data from January 2007–December 2019.
Institutional bone banks are the widely accepted source of allogenic bone grafts. They are liable for their harvesting, testing, and storage according to strict protocols. Reference Kappe, Cakir, Mattes, Reichel and Flören1 Between 1% and 22% of the donated bone grafts are contaminated and thus rejected; disease transmission possible if the bone allograft is contaminated. Reference Tomford, Thongphuasuk, Mankin and Ferraro2–Reference Barnhart, Allan, Milbrandt, Khardori, Hall and Barenfanger4 High-quality measures in the prevention of bone allograft contamination during retrieval and storage must be provided by any bone bank, particularly when sterilization procedures are not applied. Reference Pruss, Seibold and Benedix5
Methods
We performed a retrospective observational cohort study involving 895 adult orthopedic inpatients at the University Clinical Center Kragujevac, in Kragujevac, Serbia, using data from January 2007–December 2019. The analysis of institutional bone banking was conducted after 2 audits including 562 donors and 333 recipients. The first audit was held from January 1, 2007, to May 31, 2013. During this period, fresh femoral head allografts were retrieved from 295 patients with femoral neck fracture or after primary total hip arthroplasty (THA). The second audit was conducted from June 1, 2013, to December 31, 2019, and 267 allografts were retrieved.
Swab samples were sent to the hospital laboratory for microbiological evaluation. Two cultures of aerobic and anaerobic microorganisms in blood agar, MacConkey agar, and chocolate blood agar were analyzed. The donors were tested for hepatitis B (HBs antigen and anti-HBc-antibodies) and hepatitis C (HCV-antibodies and HCV-RNA), human immunodeficiency virus (HIV1/2 antibodies), and syphilis (VDRL) at donation and 6 months after surgery, according to the bone bank protocol. Acceptable bone allografts were ready for use 6 months after admission and were stored for a maximum of 5 years. To prevent bone allograft contamination during thawing, we immersed it in a 0.9% saline with an extremely high concentration of bactericidal antibiotics (eg, amikacin or clindamycin) according to the standard procedure of our bone bank.
Bone allograft-related surgical site infections (SSIs) were recognized and analyzed by surgeons and institutional infection control personnel according to widely accepted surveillance methods for SSI. Reference Anderson and Perl6
Results
The ratio between the overall number of procurement procedures and the origin of bone allografts was statistically highly significant in the second audit compared to the first survey (Table 1). The overall rate of discarding bone allografts after 13 years of bone banking was 26.86%. There was a significant decrease in allograft contamination from 12.54% during the first audit to 4.49% in the second survey (P < .05). The inability to perform serology retests after 6 months (15.72%) in the second survey significantly increased compared to the first audit (7.11%; P < .05).
Table 1. The Ratio Between Two Audits Concerning the Overall Number and Type of Donor and Recipient Procedures, the Number of Discarded Allografts Due to Bacterial Contamination, and Serology
Note. THA/HA, total hip arthroplasty/hip arthroplasty; ORIF, open reduction internal fixation.
a P < .05 indicates a significant difference.
b Death, refusal, or underbudgeting.
The organisms most commonly identified were Staphylococcus spp in both audits. No statistical significance was found between the 2 audits concerning the number of particular surgeries. The exception was a significant decrease in the number of allografts used in revision trauma surgery in the second survey compared to the first survey (P = .01). The overall allograft-related infection rate after 13 years of bone banking was 1.80%. Moreover, 4 recipients (2.22%) in the first survey developed surgical site infections (SSIs) following trauma surgery. Coagulase-negative Staphylococcus and methicillin-resistant Staphylococcus aureus (MRSA) were isolated in 3 of 4 surgical site infections. The fourth patient suffered from polymicrobial infection caused by Enterococcus faecalis, Proteus mirabilis, and Pseudomonas aeruginosa. During the second survey, 2 recipients (1.30%) developed SSIs, one following adult scoliosis surgery, and the other following revision THA. Furthermore, 2 germs, Acinetobacter and methicillin-sensitive Staphylococcus aureus (MSSA), were isolated at the surgical site of the first recipient, and Staphylococcus epidermidis was found in the second recipient.
Discussion
Our results show that the hospital bone bank system operates in compliance with the high international standards, and with a low infection rate among recipients. Femoral head allografts retrieved from living donors are safe. The overall discarding rate of 26.86% correlates with 12%–33% in earlier reports. 7,Reference Nielsen, Larsen, Andersen and Ovesen8 The leading cause of allograft rejection during the first survey was allograft contamination, which led us to develop a more efficient allograft handling technique during harvesting. The inability to perform serology tests due to underbudgeting, donor death, and donor refusal to perform the serology retests was the leading cause of allograft rejection over the past 7 years. Surgical site infection (SSI) as a repercussion of the contaminated bone allograft is uncommon and ranges between 1.3% and 12%. Reference Kappe, Cakir, Mattes, Reichel and Flören1,Reference Nielsen, Larsen, Andersen and Ovesen8,Reference Fu, Liu and Huang9 The overall allograft-related infection rate after 13 years of bone banking was 1.80%. The organism most commonly identified was the Staphylococcus spp in both audits.
In addition to favorable results of stringent aseptic allograft handling, we have faced inadequate institutional support and donor disinterest to participate in bone banking over the past 7 years. Both are extremely important for its efficient functioning and existence. Further improvements in bone allograft procurement are needed to reduce bacterial contamination and infection rate, as well as a well-controlled, randomized clinical trial using different techniques of allograft handling and processing, which would be of significant contribution to the medical community.
Supplementary material
To view supplementary material for this article, please visit https://doi.org/10.1017/ice.2021.102
Acknowledgments
Financial support
No financial support was provided relevant to this article.
Conflicts of interest
All authors report no conflicts of interest relevant to this article.
