Carlos Lee's home run capped a three-run rally off Isringhausen in the ninth inning of a 3-2 victory Friday night for their sixth straight victory.
"He left it middle in, a mistake, and I took advantage of it," Lee said. "I don't know if we got lucky or it's just the way we're going right now.
"We just went out there and put some hits together at the right time."
Miguel Tejada had an RBI triple and Lance Berkman's sacrifice fly for the second out tied it before Lee hammered a first-pitch fastball well over the left-field wall, a drive estimated at 396 feet, for his fifth homer. Isringhausen (1-2) has eight saves in 10 chances but has taken the loss in two of his last three outings and allowed runs in four of his last six appearances.
"Just bad location," Isringhausen said. "Just a bad pitch to Carlos Lee. I have no excuses, I just didn't make the pitches I needed to make."
Wesley Wright (3-0) had two strikeouts and a walk in the eighth. The Cardinals had a runner on third with one out in the bottom of the ninth before Jose Valverde finished for his fourth save in seven chances.
Looper worked seven innings of two-hit ball for St. Louis. Houston's Shawn Chacon survived early wildness that led to both of the Cardinals' runs in the first, allowing one earned run and five hits in seven innings with a season-high six walks.
"I was a little stiff coming out and didn't really get loose until the third inning," Chacon said. "That just goes to show you that if you keep the score close, you can come back and win."
The winning streak is the Astros' longest since Sept. 20-28, 2006, when they won nine straight. The start of the game was delayed for two hours by heavy rain.
"We're getting big hits, good pitching, good defense," manager Cecil Cooper said. "Those are the things that win ballgames. This was probably the biggest win we've had."
Adam Kennedy's bases-loaded, two-out infield hit in the first combined with third baseman Geoff Blum's throwing error was the only play that created runs before the ninth. Albert Pujols had an infield hit and walked twice and has reached base in all 24 games for the Cardinals.
Chacon got himself in trouble in the first, walking three of the first four hitters. He retired Pujols, the No. 3 hitter, on a popup, and caught fifth-place hitter Troy Glaus on a called third strike before Kennedy's dribbler between third and short combined with third baseman Blum's wild, backhand toss gave the Cardinals a 2-0 lead.
Blum had trouble getting the ball out of his glove after going to his left to field Kennedy's grounder, finally delivering a wild backhand toss in the general direction of second base that ended up in short-center field. The Cardinals missed a chance for more in the second, loading the bases on two hits and a walk before Glaus struck out again. Glaus left the game after the at-bat, complaining of watery eyes and blurred vision.
Glaus said the problem only occurs during night games at home and believes the problem is allergies. St. Louis is well-known for its high mold content.
"We're trying to get them under control," Glaus said. "I've never had allergies before in my life, so I'm not sure what to do about them."
The Cardinals avoided injury in the first when left fielder Chris Duncan nearly ran over center fielder Rick Ankiel when both converged on Berkman's short pop fly. Duncan made the catch for the third out.
Children of the new St. Louis Rams owners, Chip Rosenbloom and Lucia Rodriguez, threw out the first pitch. ... Hunter Pence singled in the eighth and is 14-for-29 (.483) during an eight-game hitting streak. ... Blum's error was only the ninth for the Astros, who entered the day tied with the Royals for the fewest in the majors. ... The Cardinals have outscored the opposition 15-1 n the first inning. ... Looper has a 2.50 career ERA against the Astros and hasn't allowed a home run against Houston in 79 1-3 innings.