the hard (and scary) way for me too

The slightest graze from a nasty bit of coral at Exmouth. Just a small red itchy spot on my knee that didnt even look like broken skin.
Two days later was the first of seven days bed rest in Exmouth hospital being monitored on some seriously serious antibiotics. They had 3 treatment options for the particular infection I had 'caught'.
1) the antibiotic I was put on first. Hugely expensive, canberra approval etc etc
2) one other even more serious & costlier antibiotic
then
3) amputation from the hip.

I kid you not - thats for real.
And its not all that uncommon in tropical reef areas.
A simple washdown with peroxide or disinfectant on the day would (almost certainly) have prevented any problem at all.