i thought it was 72 for most bacteria, and 120 for those that go dormant. either way, wiping the knife shifts the physical dirt and have a good dram to wash the food down and you'll be fine.
most cleaners talk about killing 97% or something, problem is that just leaves the really strong 3% with alot more space to multiply. one idea in surgery (allegedly - can't find a link now) is for docs to scrub and then apply live yoghurt to their skin - the live bacteria are harmless to humans and simply take up the space that the harmful bacteria would otherwise multiply into. its an interesting idea...
or just have another dram