I don't think you should be an Auror, Harry," said Luna unexpectedly. Everybody looked at her. "The Aurors are part of the Rotfang Conspiracy, I thought everyone knew that. They're working to bring down the Ministry of Magic from within using a mixture of dark magic and gum disease. — J.K. Rowling
Under Kingsley Shacklebolt, Azkaban was purged of Dementors. While it remains in use as a prison, the guards are now Aurors, who are regularly rotated from the mainland. There has been no breakout since this new system was introduced. — J.K. Rowling