ST. LOUIS -- The latest victim of the virus infiltrating the Mets' clubhouse is outfielder Jason Bay, who sat out Tuesday's series opener at Busch Stadium. Bay planned to see a doctor at some point during the day for a more accurate diagnosis of his malady.

"He's concerned about it being something he's going to need some medication for," said Mets manager Terry Collins.

Bay, who is batting .357 with three home runs and seven doubles over his past 16 games, is merely the latest in a string of Mets players to suffer from illness; pitchers Chris Capuano and Tim Byrdak have both complained of symptoms in recent days.

The Mets did receive a boost Tuesday from the return of outfielder Angel Pagan, who missed one game with a sore quadriceps muscle. He collected three hits and drew a go-ahead walk in the seventh inning of the Mets' 11-6 loss to the Cardinals.

Though Collins called Pagan's injury "a small issue," he noted that the training staff will "certainly have to keep an eye on him" throughout the final nine games of the season.

Pagan, who entered batting .269 in September, has not hit a home run in a month and has more than doubled his career total with 10 errors in center field.

Izzy's return to St. Louis won't see live action

ST. LOUIS -- Jason Isringhausen stepped into his car Tuesday afternoon and made the relatively quick drive to Busch Stadium, along the same route he had traversed more than 400 times before.

"It's just highway all the way here," Isringhausen said after stepping foot into the visitor's clubhouse for the first time in his life.

Isringhausen's return to St. Louis, where he won a World Series ring in 2006 and spent nearly half of his 15-year big league career, was not as memorable as he might have hoped. Unable to pitch due to the residual effects of a herniated disc in his lower back, Isringhausen planned only to throw a bullpen session this week in the hopes of finishing out the season back in New York.

But more than a month removed from his 300th save, in the city where he recorded 103 of them, Isringhausen did have a chance to reflect back on his renaissance season with the Mets.

"I didn't know what was going to happen," he said. "I just wanted to try out this spring and everything worked out."

Everything worked out better than even Isringhausen could have imagined, coming off more than year of rehabilitation and fruitless efforts to make it back to the Major Leagues. His story, at age 39, is by this point well-documented: the Mets took a chance on their former blue-chip starting-pitching prospect, Isringhausen made the team and even rediscovered a bit of his old glory.

"I just felt like I had unfinished business," Isringhausen said. "I wanted to go out on my terms, so to speak, and injuries weren't letting me do that."

Now, assuming he remains healthy enough to pitch next season, Isringhausen plans to return to the big leagues -- if not in New York, then elsewhere. His 4.05 ERA and 44 strikeouts in 46 2/3 innings are evidence enough that he can still pitch.

His aspirations remain, as well.

"I have the desire to stay home with the girls, but then I have that desire for competition," Isringhausen said, referring to his two young daughters. "We can do all the hunting and softball-playing we want, but it's just not the same as going out and facing the great hitters of the game.

Worth noting

• The Mets have stranded 86 runners on base over their past eight games, including 13 in Tuesday's 11-6 loss, upping their Major League-leading total to 1,204.

• Lucas Duda entered Tuesday with a .322 batting average since the All-Star break, which ranks sixth in the National League. His .404 on-base percentage ranks fourth.

• The Mets lead the NL and rank third in the Majors with 543 walks. They drew nine on Tuesday.