The Career Education Corporation, operator of the Katherine Gibbs secretarial schools and for-profit colleges, said two of its colleges were being reviewed by organizations that certify them. American InterContinental University was put on ''warning status'' by the Commission on Colleges of the Southern Association of Colleges and Schools, and Brooks College has been put on probation by the Accrediting Commission for Community and Junior Colleges of the Western Association of Schools and Colleges, Career Education said.