...There is bacteria and wild yeast everywhere. If one is getting an infection then it is most likely coming from unclean/unsanitized equipment or somewhere in the environment...
Use separate soft parts on the cold side and you can stash lagers and lambics in the same room/kegerator.
From past threads on this forum, there are some items brewers forget to segregate:
- Lid of plastic fermenter
- Carboy/starter flask bungs
- plastic tubing for oxygenation stone
- ALL of the auto-siphon (don't get the inner tube or end cap mixed up)
- muslin bag for straining/spicing/dry hops
- keg o-rings and poppets
- Liquid Quick Disconnect
EVERYTHING that you use on brett/sour beers should be segregated and marked. Permanent marker is okay but can wear off. Red tape is better.