Root rot in gritty mix?? That is really hard to do!! Are you sure that's what the problem was?

You can effectively sterilize the soil mix by watering it thoroughly with boiling water. And by thoroughly, I mean dousing it several times with boiling water so the mix is saturated, allowing it to drain well, stirring it up and dousing again. I would also second the cleaning of the pot inside and out with the bleach solution.

you can also sterilize media.. by wetting it.. and then either baking it.. or heating it in the microwave ... imo ... when it starts steaming ... you are all set ..

ken

http://tipnut.com/sterilize-soil/

But it will stink up your kitchen!!

@gardengal48 I find it pretty easy to kill a succulent in gritty mix. It usually requires you to repot and water right away before the roots heal. It also helps if temperatures are cooler, near the limit of what that species can handle.

I have also lost plants to overwatering in gritty mix. I lost a few during the winter. One was only getting rain water outside. There were three escheveria "white ghost" in a large container, and one of the three got root rot and I was unable to save it. The other two are fine. The others I have lost were before I understood that succulents need very little water. I was watering every other day when the plants only needed once a week. That was a similar situation where three plants were in a container, and one of those got root rot and was a total loss. The other plants continue to do well.

Here is a thread discussing an Adenium I lost in gritty mix, right after a repot, where I made the mistake of watering the new pot immediately after the repot:

https://www.gardenweb.com/discussions/5059141/looks-like-i-killed-my-first-adenium-arabicum

That sort of root rot is water-related, not a disease. Succs just need very little moisture usually so if the media stays wet (like with exposure to frequent rainfall), then the root simply drown. No need to sterilize soil or the container in that case. Just keep the subject plants out of the rain :-) A covered porch or under the eaves or under a deck.