St. Louis ? Mike Martz is out indefinitely as coach of the St. Louis Rams because of a bacterial infection of the heart.

Martz was told by a specialist Monday that his condition, which kept him out of two practices last week, had worsened. The 54-year-old has been ill for more than a month and was tested for endocarditis, a bacterial infection of the lining of the heart or a heart valve.

After the Rams’ 37-31 loss Sunday to the Seattle Seahawks, Martz said he shouldn’t have been on the sideline. St. Louis dropped to 2-3.

Rams president John Shaw said Monday that Martz would be hospitalized four to 12 days but would not speculate on the length of his absence. Shaw said he wasn’t told the specific name of the illness, but was led to believe that Martz’s heart valve had weakened since last week.

The antibiotics that Martz began taking Friday didn’t seem to help, Shaw said, but he didn’t know if additional procedures would be necessary. Severe cases of endocarditis can require open-heart surgery.

Assistant head coach Joe Vitt will take over as coach. Martz told his players during a brief but emotional team meeting that he would step aside, Vitt said.

“The team is his concern,” Vitt said. “His health is our number-one concern.”

Martz spoke with a raspy voice after Sunday’s game, but sounded optimistic about his health. Still, he said that in retrospect he should have allowed offensive coordinator Steve Fairchild to run the show.

“I wasn’t myself this week, the game plan wasn’t clear for me,” Martz said. “It’s over with now, but I just feel what happened to me has affected this team, and that breaks my heart.”

Martz first was hospitalized Sept. 30 because of what was thought to be a sinus infection.