Resistance to infection of long-term cryopreserved human aortic valve allografts.
OBJECTIVE
To analyze the in vitro antimicrobial activity of 3 antibiotic regimens (group A, gentamicin-piperacillin-vancomycin-metronidazole-amphotericin B; group B, gentamicin-piperacillin-flucloxacillin-metronidazole-amphotericin B; and group C, meropenem-vancomycin-tobramycin-colistin-amphotericin B) used in the processing of cryopreserved human ascending aortic tissue and aortic valves against Staphylococcus epidermidis and Staphylococcus aureus. The results were additionally compared with the infection resistance of cryopreserved ascending aortic tissue against Escherichia coli and Pseudomonas aeruginosa.


MATERIALS
Each of 10 cryopreserved human allografts (CHAs) was divided into 25 pieces (separating aortic wall and valve). Eighteen segments were microbiologically tested, and 7 pieces underwent scanning electron microscopy. A bacterial solution (4 mL; optical density, 0.20 ± 0.02) was used for contamination. After incubation, the optical density of the solution was measured. CHAs underwent sonication to release viable adherent bacteria. The number of attached bacteria was quantified by the colony forming units per square centimeter of CHA surface.


RESULTS
Antibiotic regimen groups B and C were more efficient than group A in eradicating gram-positive organisms adherent to the aortic wall (P < .001). Group C showed enhanced resistance against E coli compared with group A or B (P < .001), whereas group B appeared to be more effective against P aeruginosa (P < .001). With reference to each antibiotic regimen, ascending aortic tissue showed significantly less bacterial contamination with staphylococcal bacteria than valve grafts (P ≤ .01).


CONCLUSIONS
CHAs possess antibacterial activity despite long-term storage over 5 years. Antibiotic combinations applied during CHA processing have a significant influence on their infection resistance. Ascending aortic tissue shows a significantly enhanced bacterial resistance against staphylococcal bacteria compared with aortic valves.
['Steffen|Viola|V|', 'Marsch|Georg|G|', 'Burgwitz|Karin|K|', 'Kuehn|Christian|C|', 'Teebken|Omke E|OE|']
D000293:Adolescent D000328:Adult D064591:Allografts D000900:Anti-Bacterial Agents D019072:Antibiotic Prophylaxis D001021:Aortic Valve D002648:Child D015925:Cryopreservation D005500:Follow-Up Studies D006084:Graft Rejection D006085:Graft Survival D006801:Humans D008826:Microbial Sensitivity Tests D008875:Middle Aged D016459:Prosthesis-Related Infections D018570:Risk Assessment D013203:Staphylococcal Infections D013211:Staphylococcus aureus D013212:Staphylococcus epidermidis D014019:Tissue Donors D016896:Treatment Outcome
aortic valve cryopreserved human allograft ascending aorta bacterial infection infective endocarditis prosthetic graft infection