In counties having a population of less than 1,000,000 and having an approved county tuberculosis hospital, the board of supervisors, by a 2/3 vote of the members elect, may create and appoint a board of county institutions for the purpose of maintaining and operating a county tuberculosis hospital, a county medical care facility and a county psychiatric facility; or may operate and administer as a single medical institution. The board may be abolished by a 2/3 vote of the members elect of the board of supervisors.