Princeton health authorities have confirmed at least 17 cases of salmonella at Princeton University and are investigating 70 other cases of stomach problems at the school that may be related to the bacteria.  Princeton spokeswoman Cass Cliatt says the most recent patient diagnosed got sick last week. Lab tests for salmonella take at least three days.  On Friday, the university stopped serving some produce as a precaution. It also closed a salad bar and a Mexican food station at the campus center’s dining facility.  Officials have interviewed 135 sick and healthy subjects at the school to try to track a common food source.