For the most part, patients are contracting fewer infections inside Massachusetts hospitals — but some problem spots remain, according to new numbers from the state's Department of Public Health. It's almost impossible to compare the quality of specific hospital procedures, but you can make a few hospital system comparisons. For instance, the latest data show lower rates for three types of hospital infections — central line and surgical site infections for hysterectomies and colon operations. On the other hand, rates for urinary tract infections from catheters have increased. Still, required reporting is spurring change, says Patricia Noga, VP for Clinical Affairs of the Massachusetts Hospital Association.