Validation of RESEP, a device for elimination of antibiotics from liquid samples undergoing microbiological analysis in tissue banking EATB 2014

Background: Antibiotics can interfere with microbial growth during microbiological analysis and lead to false negatives. The aim of the study was to validate the RESEP syringe device in terms of elimination of antibiotics and recovery of microorganisms from samples undergoing microbiological analysis and to evaluate its compatibility with automated microbiology systems and tissue bank processes.

Materials and methods: The elimination of Streptomycin, Penicillin G, Gentamicin, Cefotaxime, Vancomycin, Amphotericin B deoxycholate from 3-9 ml of different corneal preservation media (EUSOL-C, TISSUE-C and CARRY-C) and a tissue decontamination medium (BASE.128) was determined by HPLC after 20 minutes of treatment with the RESEP syringe.
The recovery of living microorganisms from 3 ml of antibiotic media inoculated with 1-10 and 10-100 CFU of S Aureus, P. Aeruginosa, C. Albicans, B. Subtilis, A. Niger and C. Sporogenes was determined by dilution plating method after 20 minutes treatment with the RESEP syringe. The tissue bank operators treated 20 samples of cold storage media with the RESEP syringe in order to evaluate the ease of use, operation time, volume compatibilities and time to detection of automated systems (Bactec BD, BactAlert Biomérieux and H&B Alifax).

Results: Before RESEP syringe treatment, the concentration of antibiotics (Streptomycin, Penicillin G, Gentamicin, Cefotaxime, Vancomycin) in the tested media ranged from 110 to 140 μg/ml. Amphotericin B deoxycholate concentration was approximately 20 μg /ml. For all the tested media, total elimination of antibiotics was observed after 20 minutes of treatment with the RESEP syringe.
Microbial recovery of 1-10 and 10-100 CFU was obtained for all investigated strains and from all the tested media. The RESEP syringe was compatible with tissue bank processes and all the evaluated microbiological systems. The RESEP syringe treated samples reduced significantly the time to detection and resulted in additional positive samples when compared to by automated systems without using the RESEP syringe.

Conclusions: The RESEP syringe was validated for elimination of antibiotics from all tested media and recovery of 1-10 and 10-100 CFU from tested samples. The simple and fast use of the RESEP syringe was compatible with the tissue bank processes and allowed to enhance the performance of the automated microbiology systems used by the tissue banks.