Doctors Gottfried Locker and Christoph Zielinski say the 48-year-old ex-front man for the pop group "Wham!" is still hospitalized. They said in a statement that he "needed intensive care because of the seriousness and spread of the infection."
Despite his progress, the doctors say Michael needs "absolute rest and restraint."
Michael was admitted to Vienna's AKH hospital last week after canceling a performance in the Austrian capital.
The singer has postponed dates in Liverpool, Sheffield, Newcastle, Glasgow, Birmingham, Manchester and London. According to a statement from his publicist, the concerts will be rescheduled. Michael had played 45 dates on his "Symphonica" European tour before falling ill.
The Associated Press contributed to this report.