Preston, with just one defeat in 14 games survived an early scare when Phil Jagielka's low cross from the left evaded Steven Kabba and Bromby just failed to connect as the ball flashed inches wide of the far post.
The visitors almost found a way through in the 20th minute, Eddie Lewis picking out Paul McKenna whose low shot was smothered on the line by Republic of Ireland keeper Paddy Kenny.
Impressive Preston were foiled again by the United keeper minutes later after full-back Graham Alexander found space to pump in a low centre. Cresswell pulled the ball down and snapped in a low drive that was scooped up by Kenny.
Billy Davies' side were in control of the game, but they were rocked when Brian O'Neil failed to clear Jon Harley's deep corner and Bromby steamed in to smash the ball into the roof of the net from close range, his fifth goal of the season.
Michael Tonge saw a shot deflected wide before Harley almost snatched a second on 42 minutes. He kept his cool after his free-kick bounced off the wall and smashed in the rebound, the ball taking a wicked deflection as it looped over keeper Chris Day and onto the top of the bar.
Cresswell snatched the equaliser in the 47th minute when United failed to clear Chris Sedgwick's corner and the Preston striker finished with an impressive overhead kick from eight yards.
David Nugent was denied by Kenny minutes later, the United keeper blocking his stinging 20-yard shot as the spoils were eventually shared.