Hi @DAN92!
Thanks for joining us! 
If you take a look at the links provided in the Welcome section you will see that the forum has a Search function. That is the place to look for information on Sapienmed audios. If an audio is no longer available, as does happen from time to time, you would find out the most current status including any substitutions or newer versions that might be available.
There is a section of the forum called Requests and Fields where you can read and make audio requests. There are some areas of the forum where a member must have a certain participation level to access. You will also find that discussed in the Newcomers Links section.
If you go to this page and read through the entire thread, you will see the current status, if any is mentioned: The Bacteria and Fungi Apocalypse
On Sapen’s Patreon (membership required) you can find The Smart Bacteria Slayer