Bacteriostasis testing on allograft tissue inoculated in WilkinseChalgren broth V. Saegeman a,b , N. Ectors b, *, D. Lismont b , B. Verduyckt b , J. Verhaegen a a Department of Microbiology, UH-KU Leuven, Leuven, Belgium b Tissue Banks, UH-KU Leuven, Leuven, Belgium Received 20 September 2007; accepted 31 July 2008 Available online 16 September 2008 KEYWORDS Bacteriostasis; Gentamicin; Sterility testing; Tissue allografts Summary Tissue banks culture tissue specimens to confirm the absence of viable micro-organisms after decontamination with antibiotics. It is pos- sible that antibiotic residues attached to decontaminated tissue are intro- duced into enrichment culture media. These could have an inhibitory effect on the culture results and generate false-negative results. Our aim was to detect bacteriostasis in WilkinseChalgren broth inoculated with bone and tendon remnants. These remnants had been soaked in a solution containing gentamicin as part of the tissue-processing procedure. We used the United States Pharmacopeia method for bacteriostasis testing with gentamicin-susceptible Pseudomonas aeruginosa American Type Culture Collection (ATCC) 15442, Staphylococcus aureus ATCC 6538, Bacillus subti- lis ATCC 6633 as test strains, and gentamicin-resistant Candida albicans ATCC 90029 as control. The residual gentamicin concentration in the broths was determined and gentamicin-soaked tissue was placed on Muellere Hinton agar inoculated with a staphylococcal suspension. Bacteriostasis was present in 53e75% of the reference test strains. Tendon remnants had a significantly higher rate of bacteriostasis (85%) than bone remnants (28%). Broths inoculated with tendon remnants had the highest residual gentamicin concentrations. ª 2008 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. Introduction Tissue banks pursue the safety of the allografts that they procure. Since tissue allografts are known to have transmitted infectious diseases, * Corresponding author. Tissue Banks UH-KU Leuven, Here- straat 49, B-3000 Leuven, Belgium. Tel.: þ32 16 345 485; fax: þ32 16 345 480. E-mail address: nadine.ectors@uz.kuleuven.ac.be 0195-6701/$ - see front matter ª 2008 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2008.07.020 Journal of Hospital Infection (2008) 70, 278e283 Available online at www.sciencedirect.com www.elsevierhealth.com/journals/jhin