They said she died of a generalized infection and abdominal bleeding.
National news websites, including G1, O Globo and Estadao, quoted authorities confirming the information.
Doctors at the Dorio Silva Hospital in Serra, in the southeastern state of Espirito Santo, earlier this month amputated Bridi's hands and feet because of irreparable tissue damage caused by a urinary infection.
She was diagnosed with the Pseudomonas aeroginosa bacterium, which can prove fatal.
Bridi was an up-and-coming model before the tragedy struck.
She twice made it into the national finals for the Miss World contest, and last year traveled to China to participate in the Miss Bikini International pageant.
Her family and media on Friday had launched an appeal for blood donors to help Bridi, who had the rare O negative blood type.
"It is important to stress that, in Mari's 20 years of life, she lived intensely and was very happy," the family said in their statement.
O Globo said Bridi was to buried late Saturday.