For over a century, brain material has been used in microbiological media. Since the emergence of bovine spongiform encephalopathy (BSE) in the late 1980s, the risk of brain and brain stem materials has been widely recognised. In culture media manufacture, some changes in sourcing of brain materials has occurred, but it remains in use.
Brain materials’ continued use in media is from a presumption that it provides extra, essential nutritive qualities. However, our recent review of the literature into the original uses of brain infusion highlighted that those reasons for its inclusion are totally unrelated to the actual performance of the media today. Those historical rationales, and the fact it is present only in homeopathic quantities, suggests that its removal will not adversely affect performance.
Performance testing of heart infusion media, compared with media also containing brain infusion, was undertaken. Our testing confirmed that, with the range of organisms tested, the minute quantities of brain materials did not provide any advantage regarding media performance. With these results in mind, the question is: does the inclusion of brain and brain stem materials in microbiological media have any place in the 21st century?