Validation of RESEP for microbiological testing of cornea organ culture medium

Abstract: The aim of this study was to validate the microbiological testing of cornea organ culture medium according to the European Pharmacopoeia using blood culture bottles and the automatized BACTEC system (BD) after removal of antibiotics with the new medical device RESEP (AL.CHI.MI.A. Srl, Italy).
For the validation, 10-100 CFU of Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, Bacillus subtilis, Aspergillus niger, Clostridium sporogenes, Enterobacter cloacae and Staphylococcus epidermidis were inoculated in 9 ml of cornea organ culture medium (MEM with 2% fetal calf serum and antibiotics, Biochrom). The medium was treated with RESEP for 20 min., inoculated in BACTEC blood culture bottles and incubated until a positive reading or for at least 14 days at 36 ± 1°C. Medium control samples, containing the same microorganisms, were inoculated in BACTEC vials without RESEP treatment. Microbial growth was controlled by direct  inoculation of BACTEC flasks (growth control).
The antibiotics were completely eliminated after 20 min. of treatment with RESEP at room temperature (confirmed by HPLC). In RESEP treated samples, the growth of all microorganisms was detected within 3 days of incubation in BACTEC system and showed no significant delay in comparison with the growth controls. Without the use of RESEP, several tests with Staphylococcus aureus, Enterobacter cloacae and Bacillus subtilis samples were not detected and other strains showed a prolonged detection time compared to treated RESEP samples and growth controls.
The microbiological testing of cornea organ culture medium with automatized BACTEC blood culture system could be successfully validated using RESEP for the removal of antibiotics.