I think most bacteria are killed at between 60 and 70 Deg C. That's 140-158 Deg F in old money for our American readers
The acanthamoeba kerititis, which is the potentially devastating one, is quite resistant to removal and I think you will find that 60-70 deg C is way above the temperature that people comfortably shower at.
But lets's put the risk into perpspective. Someone yesterday quoted the risk of acanthamoeba kerititis infection as 1 in one million
contact lens wearers. The only cases of infection I have read about are to people cleaning their lenses in tap water and then inserting the lens into their eye.
So, although acanthamoeba kerititis could theoretically be found just about anywhere (salt, fresh, brackish, bottled, tap water, air, earth, etc). it is quite rare and actual infections very rare. These can be minimised by taking the normal sensible precautions and following good practice cleaning your
contact lenses and case, with preferably a two step peroxide disinfecting solution (the one step peroxide system just doesn't cut it for killing acanthamoeba infections).
So, no, the hot shower water is not hot enough to kill the beasties, but I normally shower with my lenses in. If you want to be super safe, then take them out before you shower.
knotlob