The Astros seemed set to break their long skid when they took a 5-4 lead into the ninth but they couldn't hold the advantage.
Rhiner Cruz (1-1) allowed a one-out single to Michael McKenry and then issued consecutive walks to pinch-hitters Sutton and Casey McGehee to load the bases. Xavier Cedeno came in to pitch and surrendered a game-tying sacrifice fly to Starling Marte, which sent Sutton to third.
Then, with Rod Barajas at the plate, Cedeno uncorked a wild pitch, and the Astros remained winless since July 16.
McKenry finished 3-for-4 with a solo homer and Tony Watson (5-1) picked up the win for the second-place Pirates, who remained two games behind the National League Central-leading Cincinnati Reds.
Chris Johnson collected three hits, including a solo homer, while Ben Francisco went deep and added an RBI single for Houston.
Senate Democrats to pull all-nighter on climate change
Interpol investigating stolen passports on missing flight