title: From penicillin-streptomycin to amikacin-vancomycin: antibiotic decontamination of cardiovascular homografts in Singapore.
abstract: BACKGROUND
  In 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.
  
  
  OBJECTIVE
  The 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.
  
  
  METHODS
  Based 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.
  
  
  RESULTS
  Tissue incubation at 4°C for 24 hours is optimal for both antibiotics, especially for amikacin, as its potency falls drastically at 37°C.
  
  
  CONCLUSIONS
  The 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.
authors.affiliation: National Cardiovascular Homograft Bank, Department of Cardiothoracic Surgery, National Heart Centre Singapore, Singapore, Singapore. heng.wee.ling@nhcs.com.sg
authors.forename: Wee Ling
authors.initials: WL
authors.lastname: Heng
authors.forename: Chong Hee
authors.initials: CH
authors.lastname: Lim
authors.forename: Ban Hock
authors.initials: BH
authors.lastname: Tan
authors.forename: Maciej Piotr
authors.initials: MP
authors.lastname: Chlebicki
authors.forename: Winnie Hui Ling
authors.initials: WH
authors.lastname: Lee
authors.forename: Tracy
authors.initials: T
authors.lastname: Seck
authors.forename: Yeong Phang
authors.initials: YP
authors.lastname: Lim
mesh_terms: D000583:Amikacin / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects / Q000302:isolation & purification; D001807:Blood Vessel Prosthesis / Q000382:microbiology*; D003666:Decontamination / Q000379:methods*; D006801:Humans; D008826:Microbial Sensitivity Tests; D010406:Penicillins / Q000494:pharmacology*; D012846:Singapore; D013307:Streptomycin / Q000494:pharmacology*; D013696:Temperature; D013997:Time Factors; D014184:Transplantation, Homologous; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D010406:Penicillins; D014640:Vancomycin; D000583:Amikacin; D013307:Streptomycin