I live with my two brothers. My parents are currently in a foreign country.

One of my brothers is in his late twenties. He has a poor credit and income. We are working very hard and going to college full-time to keep up with the costs (bills, rent, etc... ), however, he is part-time in college and won't contribute that much to the family. We have tried talking to him, but he keeps changing the subject and gets defensive. Our parents have talked to him, but they haven't had much luck.

I'm not sure what route we should take, as I have spent all of my savings, and used my credit lines to keep up. I'm thinking about moving out and finding other roommates...

He is still your brother! They need you. Don't worry, you will not lived with them forever. If you finish your studies then that's the time to move out. You cannot change him, no person has the power to change another person. But it doesn't mean he will not change.Someday he will.

Family can often be the worst people to try and live with and share. Exact money to be paid by each should have been agreed to before moving in.

Who owns the house you are living in ? Is it owned by family or just a home you are renting together.

Whose name is on the lease ( if rented)
Was there agreements on who pays what.

It is not fair that you or other member pays more than your share.

I would set down all together agree or demand what has to be paid, and pay no more than your share.