A comparative study of blood and bone marrow cultures in cadaveric bone donation

The Causes for the Loss of Cellular Material at the Qualification Stage and the Influence of the Patient's Flora on Culture Infection

There are several causes leading to the loss of cellular material earmarked for transplantation. This paper aims to evaluate the number of lost donors and lost cells in the culture by means of verifying both the results of the qualification tests and the presence of microorganisms in the cellular material. The analysis involved 86 donors hospitalized for thermal burns, from whom cells were harvested for keratinocyte and fibroblast cultures in the years 2011 to 2015. All potential donors underwent qualification tests: Anti-HIV-1,2; HBsAg; Anti-HCV-Ab; HBc, and a specific test for syphilis. In the case of skin fragments collected for culturing, the microbiological tests included the carrying fluid, the medium after 1 change, and the medium during culturing and before transplantation. Skin donors for cell cultures were assigned to the groups based on if the skin was collected up to 7 days following the burn or later. On average, 12% of the disqualifications were reported among donors for cell culturing. The most frequent cause of donor disqualification (54% of all disqualifications) was a positive HBc(+). The occurrence of fungal infections detected in the cellular material was over 30%. Establishing the culture after day 7 following the injury immediately increases the risk of infection by 25% in comparison to those cultures established before or on day 7 following the injury. Proper disinfection of donor place is crucial, but sometimes insufficient for maintenance sterility in cell culture. The risk of infection increases 25% after 7 following the injury.

Infections in the tissue material and their impact on the loss of transplants in the Laboratory of in vitro Cell and Tissue Culture with Tissue Bank in the years 2011-2015

Radiation sterilization eliminates microbiological infections but causes the degradation of the cell factor. The negative result of microbiological examination for tissue transplants is one of the conditions for approval for distribution in patients. The study attempts to verify impact of the presence of microbes onto material for transplant loss. In the 2011-2015 period, we analyzed 293 donors of skin and amnion. Microbiological sampling was performed. The total of 21 strains of bacteria, molds and fungi was identified in collected tissue. The widest spectrum of strains was found in skin (17), followed by amnia (8). The total number of positive findings was 147 and was again highest in skin (129), while the number of positive findings in amnia was 18 only. The general percentage of fungal infections was very low. The presence of fungal strains was only observed in allogeneic skin (2%). Large number of microorganisms isolated from the skin before sterilization was observed, so it seems impossible to use allogeneic intravital skin. However, the intravital application of allogeneic amnion obtained from cesarean section remains to be considered.

Culture methods of allograft musculoskeletal tissue samples in Australian bacteriology laboratories

Samples of allograft musculoskeletal tissue are cultured by bacteriology laboratories to determine the presence of bacteria and fungi. In Australia, this testing is performed by 6 TGA-licensed clinical bacteriology laboratories with samples received from 10 tissue banks. Culture methods of swab and tissue samples employ a combination of solid agar and/or broth media to enhance micro-organism growth and maximise recovery. All six Australian laboratories receive Amies transport swabs and, except for one laboratory, a corresponding biopsy sample for testing. Three of the 6 laboratories culture at least one allograft sample directly onto solid agar. Only one laboratory did not use a broth culture for any sample received. An international literature review found that a similar combination of musculoskeletal tissue samples were cultured onto solid agar and/or broth media. Although variations of allograft musculoskeletal tissue samples, culture media and methods are used in Australian and international bacteriology laboratories, validation studies and method evaluations have challenged and supported their use in recovering fungi and aerobic and anaerobic bacteria.

Infection not associated with use of human musculoskeletal tissue allografts

The deaths of otherwise healthy patients that are attributable to contaminated allografts have heightened concerns about the screening, processing, and use of such tissues. We present one tertiary care institution's experience with musculoskeletal allografts and determine the frequency of postoperative Clostridium infection. We used an institutional microbiology database to identify all records of culture-confirmed Clostridium infection from January 1990 through July 2006. A comprehensive musculoskeletal database was cross-referenced to include all possible allograft samples surgically collected or implanted from January 1990 through July 2004 to determine the frequency of Clostridium infection associated with use of allograft musculoskeletal tissue. Musculoskeletal allografts were implanted in 16,314 patients during the study period. After a minimum follow-up of 2 years, no patient had development of a definite Clostridium infection that was attributable to the use of musculoskeletal allograft tissue. These outcomes can be achieved with established screening and processing techniques for donor tissue.

A comparison of two microbial detection methods used in aseptic processing of musculoskeletal allograft tissues

Tissues from 78 musculoskeletal donors were concurrently tested for microorganisms using both a swab and liquid culture method. An aggregate total of 20 organisms were detected by both methods. The swab detected 4/20 organisms while the liquid culture detected 18/20 organisms. The swab method yielded sensitivity and negative predictive values of 20 and 92.3%, respectively. Comparatively, the liquid culture displayed a sensitivity of 90% and a negative predictive value of 99%. These results clearly demonstrate that the liquid culture method is superior to swab cultures in microbial detection. Additional studies are necessary to determine the optimal culture conditions for different types of tissues when utilizing the liquid culture method.

Bacterial infection transmitted by human tissue allograft transplantation

Bacterial contamination of tissue allografts obtained from cadaveric donors has been a serious cause of morbidity and mortality in recipients. Recent cases of fatal and nonfatal bacterial infections in recipients of contaminated articular cartilage (distal femur) and tendon allografts have called attention to the importance of avoiding tissue donors suspected of carrying infectious disease, of not processing donated tissue carrying virulent bacteria, the occurrence of falsely negative final sterility tests, and the need to sterilize tissues. These cases demonstrated that contamination can arise from an infected donor, during tissue removal from cadaveric donors, from the processing environment, and from contaminated supplies and reagents used during processing. Final sterility testing can be unreliable, especially when antibiotics remain on tissues. There is an increasing need for control of microbial contamination in tissue banks, and sterilization of tissue allografts should be recommended whenever possible.

The appropriateness of swab cultures for the release of human allograft tissue

Surgeries utilizing human allograft tissues have increased dramatically in recent years. With this increase has come a greater reliance on the use of swab culturing to assess allograft tissues for microbial contamination prior to distribution. In contrast to the typical industrial microbiological uses for swabs, the tissue banking industry has relied on swab cultures as a sterility release method for allograft tissues. It has been reported in the literature that swabs have limitations, both in sensitivity and reproducibility, so their suitability as a final sterility release method was evaluated in this study. Two different swab-culturing systems were evaluated (COPAN, EZ Culturette) using human allograft tissues spiked with low levels of multiple bacterial and fungal microorganisms. The average microbial recoveries for all challenge microorganisms for each tissue type and each swab system were calculated. Percent recoveries for each challenge microorganism were also calculated and reported. The results indicated that both swab systems exhibited low and highly variable recoveries from the seeded allograft tissues. Further analysis indicated there was no statistical difference ( proportional, variant=0.05) between the two swab systems. It is the recommendation of the authors that swab culturing not be used to assess relatively low levels of microbial contamination on allografts. Instead, alternative validated microbial detection methods with improved sensitivity and reproducibility should be employed and validated for this critical task.

Safety and FDA regulations for musculoskeletal allografts: perspective of an orthopaedic surgeon

The Musculoskeletal Transplant Foundation Symposium held in September 2003, in Edinburgh, Scotland provided the opportunity for an orthopaedic surgeon experienced in tissue banking and musculoskeletal allograft transplantation to summarize to orthopaedic colleagues the past and current efforts made by the Food and Drug Administration to ensure the safety of allograft tissues, aspects of tissue banking, concerns of allograft safety and future Food and Drug Administration proposals. The review allows an orthopaedic surgeon an understanding of allograft safety issues and provides information for better informed consent to be obtained by the orthopaedic surgeon from the recipient patient.

Blood and marrow cultures as indicators of bone contamination in cadaver donors

Of 770 cadaver bone donors evaluated, 185 had positive blood or ilium marrow aspirate cultures. These donors were matched with an immediately preceding or subsequent donor with negative blood and marrow cultures. Donors with cultures positive for skin contaminants only were not included in the study. Samples of the blood and bone marrow, surface swab cultures, and cultures of tissue samples of the excised skeletal tissues were obtained at the time of tissue procurement. There were 88 (48%) donors with similar microbial species recovered from the blood and ilium marrow. These donors had a higher rate of positive bone cultures (30%) than donors with positive blood (15%) or marrow cultures only (11%) or donors with negative blood and marrow culture results (7.3%). Recovery of similar isolates from the blood and marrow had a positive predictive value of 72% for the isolation of the same types of organisms from the excised tissues compared with 38% for donors with positive blood cultures only. Although not absolute predictors of tissue contamination, combined blood and bone marrow cultures were more reliable indicators of tissue contamination than blood cultures alone.

Bacterial contamination of femoral head allografts from living donors

We analyzed the bacterial contamination rate of femoral head allografts from living donors and determined the true bacterial load with cultures from the grafts in their entirety in a specially prepared medium. During 4 years we took swab cultures from 2,679 grafts of which 2,414 (90%) were negative. In a period of 12 months, grafts rejected for reasons other than infectious disease were cultured in their entirety to determine the true bacterial load. Of the 106 grafts included, 15 were contaminated. Microorganisms were isolated from 10 of the 91 initially swab culture-negative grafts (9%) and from only 5 of the 15 swab culture-positive grafts, most of which were normal skin contaminants. Swab culture negative grafts apparently may still be contaminated. It seems wise to subject all femoral head allografts from living donors to antibacterial processing.

Microbiological screening of post-mortem bone donors - two case reports

This study assesses the value of blood cultures in combination with swab culturing techniques in association with bone banking procedures. The results of blood and swab cultures of two postmortem bone donors were compared with procured grafts, cultured in their entirety. In one donor, who died of drowning, three of the 12 entire graft cultures were positive with the same microorganism of high pathogenicity as the blood culture, whilst the swab culture of only one graft was positive. In the second donor, who died from myocardial infarction, four entire cultures were positive with the same organism of high pathogenicity as the blood culture, whilst the swab cultures of three grafts were positive. In both donors identical organisms were cultured from the myocardium of the pulmonary or aortic heart valve. The results confirm the limited sensitivity of swab culturing techniques. Especially micro-organisms inside a graft, disseminated through the bloodstream, can remain unnoticed. Blood cultures seem to provide additional information on micro-organisms that have spread haematogenously pre-mortem and may even provide information on the source from which they have spread.