I got my infection from a scratch no bigger then the tip of a pencil. The scratch happened when my elbow pad rode up a hair when I was tripped. My elbow a day and a half later was bigger than a grapefruit and was over 105 degree's, it was burning up. I was very lucky that it never got to the bloodstream. I went immediately to my buddy that was a DR. and got the strongest antibiotic they make. It took quite sometime to get rid of it. The antibiotic made me sicker than excrement, it is ridiculously powerful. It was called Levaquin.
It really doesn't take much to get infected if the facility you're rehabbing or working out at has the bacteria. I nuked my elbow pads.