Silva and Dewees both tested positive for the anabolic steroid Boldenone and each have been handed down a one-year suspension and a $2,500 fine by the California State Athletic Commission.
The Commission announced yesterday evening that two positive tests would be revealed today once the athletes have been notified.
Silva won the belt at the July 26 event in Stockton against Justin Eilers.
Justin Eilers, Nick Thompson and Jake Shields, the remaining fighters on the July 26 EliteXC events, were are cleared.
Fedor Emelianenko fans can breathe a sign of relief as the Affliction fighter testing positive for a performance-enchanching drug was Dewees, who recorded a level of 499 ng/mL.
Both tests were conducted independently with "A" samples at Quest Diagnostics and "B" samples at the Laboratoire De Controle Du Dopage in Canada.
Additionally, William "Yobie" Jacobsen has been suspended indefinitely for avoiding his scheduled test for drugs of abuse at the August 15 ShoXC event in Friant.