Things like that, like reef cuts, are not worth taking lightly. Something very similar happened to me at the pond, of all places. I managed to step pretty hard on some limestone rock, one of them was fairly sharp, and penetrated my ankle area. Made it bleed but nothing more than like cutting yourself with a knife in the kitchen. In that area there is some really calm areas near the sand bar also with a fair amount of organic material under the surface, I did step into that ooze a bit as I was packing up. So what I thought, I'm in the ocean, its salt water, cleans out wounds. Thought nothing of it.
But the ocean is full of beasties. It got infected, swelled up like a balloon, oozing pus etc over about 2 weeks, so i just kept washing it, redressing it, putting betadine etc on it. It got worse, my whole leg swelled up red, then my neck started to puff up, my face...... it wasn't going well. So I went to the doctor, he sent me straight to hospital. Explained that the bugs that live in the ocean, many of them they don't even know what they are. They live in salt water, so they are tough. They checked me into infectious diseases area, swabbed it and sent of for culturing. They had me on some big time strong antibiotics (knocked my body around I tell you), steroids to reduce the swelling around my neck... I could go on, but my lesson was, if you get cut by rocks, reef or anything much in the ocean, it gets messy fast, easily. If I have any doubt about an area now, I just wear some reef shoes. Not as good "feel" in them, but I get to keep kiting.