Equifax Inc., the largest U.S. consumer credit-reporting service, said it bought 80% of a Brazilian credit-information company, Seguranca ao Credito e Informacoes, for about $197 million. Atlanta-based Equifax bought the stake from SCI's two founders, John Gottheiner and Lotario Krause. The purchase gives Equifax access to SCI's 1,000 employees, 47 branches and 21,000 clients, including manufacturers and financial institutions. Equifax expects the acquisition to cut earnings by about 2 cents a share in 1998 and 3 cents in 1999 and to add to earnings after that. SCI had 1997 revenue of about $80 million; Equifax had 1997 revenue of about $1.37 billion. SCI maintains credit files on more than 2 million Brazilian businesses and 5 million consumers. Equifax shares were unchanged at $43.69 on the NYSE.