A Michigan doctor accused of sexually abusing gymnasts was sued Tuesday by 18 women and girls, the latest legal action over alleged assaults, mostly at his clinic at Michigan State University.

The lawsuit against Dr. Larry Nassar, Michigan State, USA Gymnastics and a Lansing-area gymnastics club was filed in federal court in western Michigan. It makes claims of civil rights violations, discrimination and negligence.

The Associated Press usually doesn't name people who allege sexual abuse, but one of the plaintiffs, Rachael Denhollander, 32, of Louisville, Ky., talked publicly about the lawsuit. She said she was assaulted by Nassar while seeing him for wrist and back injuries at age 15 in 2000.

Denhollander, who was a gymnast, said she didn't file a complaint at the time because she believed her "voice would not be heard." She said Nassar was held in high esteem at Michigan State and was also affiliated with USA Gymnastics.

The abuse alleged by the 18 women and girls occurred over 20 years. They ranged in age from 9 to 29 at the time.

Most were minors "cloaked with innocence and trust of their youth," attorney Stephen Drew told reporters.

In 1999 and 2000, a Michigan State runner and a softball player complained to the university's sports medicine staff that Nassar had molested them with his hands, but no investigations were conducted, according to the lawsuit.

Nassar now faces at least five civil lawsuits. Through lawyers, he's denied the allegations. He hasn't been charged with any crimes related to his work at Michigan State, although he's charged with sexually assaulting a girl at his Holt, Mich., home.

Separately, Nassar is charged in federal court with possessing child pornography. He's being held in jail without bond.

Michigan State said it won't comment on specific allegations in the latest lawsuit. It said campus police investigated a complaint against Nassar in 2014 but no charges were filed. The school said it received no other complaints until last August.

Nassar was subsequently fired for not complying with employment requirements put in place after the 2014 complaint. Michigan State hasn't elaborated.

Campus police still are investigating Nassar with state and federal authorities. Outside lawyers also are advising the university on an internal review of his work.

Indianapolis-based USA Gymnastics said it cut ties with Nassar in 2015 when it first heard allegations about the doctor.

"We find it appalling that anyone would exploit a young athlete or child in this manner," the organization said in a statement.