From Penicillin-Streptomycin to Amikacin-Vancomycin: Antibiotic Decontamination of Cardiovascular Homografts in Singapore

Abstract

BackgroundIn February 2012, the National Cardiovascular Homograft Bank (NCHB) became the first tissue bank outside of North America to receive accreditation from the American Association of Tissue Banks. From 2008 to 2009, NCHB had been decontaminating its cardiovascular homografts with penicillin and streptomycin. The antibiotic decontamination protocol was changed in January 2010 as amikacin and vancomycin were recommended, in order to cover bacteria isolated from post-recovery and post- antibiotic incubation tissue cultures.AimThe objective of this study is to determine the optimal incubation conditions for decontamination of homografts by evaluating the potencies of amikacin and vancomycin in different incubation conditions. Retrospective reviews of microbiological results were also performed for homografts recovered from 2008 to 2012, to compare the effectiveness of penicillin-streptomycin versus the amikacin-vancomycin regimens.MethodsBased on microbiological assays stated in United States Pharmacopeia 31, potency of amikacin was evaluated by turbidimetric assay using Staphylococcus aureus, while vancomycin was by diffusion assay using Bacillus subtilis sporulate. Experiments were performed to investigate the potencies of individual antibiotic 6-hours post incubation at 4°C and 37°C and 4°C for 24 hours, after the results suggested that amikacin was more potent at lower temperature.FindingsTissue incubation at 4°C for 24 hours is optimal for both antibiotics, especially for amikacin, as its potency falls drastically at 37°C.ConclusionThe decontamination regimen of amikacin-vancomycin at 4°C for 24 hours is effective. Nevertheless, it is imperative to monitor microbiological trends closely and evaluate the efficacy of current antibiotics regimen against emerging strains of micro-organisms.

International Heart Valve Bank Survey: A Review of Processing Practices and Activity Outcomes

“…These milder techniques improved valve durability and, ultimately, patient outcome. Today, the majority of HVBs worldwide use aseptic retrieval of donor heart valves followed by low-dose antibiotic decontamination, cryopreservation, and storage at ultralow temperature until the valves are required for implantation [1–3]. …”