Here's a really comprehensive guide
Hello. These links might be helpful
How To Deep Clean a Mattress
How to Remove Pee Stains and Smell from Mattress
I would use a steam cleaner. You dont want to get your mattress to wet or you can end up with a damp smell.
Do you have a spill or just want to generally clean your mattress? More information is needed.
I have an attachment for my clothes steamer that is for upholstery, and it works well for cleaning beds, too. I have a Jiffy steamer.
If you have a steamer - you can use that to sanitize your mattress. Here's a video that might help too - https://www.youtube.com/watch?v=F7A3nH3Qaew
You can apply baking soda, let set, then vacuum up
You can use the upholstery nozzles on a carpet cleaner.
Try this: https://www.youtube.com/watch?v=b8YZkso-rtI
To generally disinfect it, you can use a clothes steamer on it.