According to the study, 70 percent of bacteria found on the equipment "are potentially harmful to humans." Additionally, gram-positive cocci, "a common cause of skin infections and other illnesses," was found on bikes, treadmills, and free weights, the three type of equipment the study looked at.
It's gross and interesting, but the sample size is very small. You can take away that bacteria is all over the gym, but it's likely there would be a lot of variance in a wide-ranging study. Your gym may be incredibly clean and the average gym may be a little cleaner than this study found. It could also be much, much worse. (It's also worth noting that EmLab P&K conducted the testing, but a company that sells home gym equipment paid for the study.)