(a) For the purpose of using such facilities, any city or county is authorized by action of its governing body to enter into contracts with an authority for such periods of time not exceeding 40 years as shall be necessary to provide for the continued maintenance and use of the facilities of an authority. Sums due and payable under such contract shall be determined from year to year during the period of such contract and no sums shall be paid for the services in excess of the amounts necessary to provide for the maintenance and operation of projects of authorities and such sums as shall be necessary to provide adequate and necessary facilities for medical care and hospitalization of the indigent sick, including reasonable reserves necessary for expansion and necessary for the payment of the cost of facilities of the projects, provided that any such contract may obligate a city or county or any combination thereof to pay for such services a fixed and definite minimum sum each year based or calculated upon the anticipated cost of such services including the cost and expense of making the facilities of the authority available for the furnishing and performance of such services. The contracts authorized under this Code section to be entered into between cities or counties or any combination thereof and an authority may provide for the conveyance or lease of any existing hospital facilities or projects to an authority created by any such cities or counties for a nominal consideration only, provided that such conveyance shall contain a clause providing that, upon dissolution of the authority, such hospital facilities or projects shall revert to the city or county conveying the same to the authority and provided, further, that no property so conveyed may be mortgaged or in any way given as security for an indebtedness of the authority; this limitation is not to be construed as limiting the right of the authority to pledge or hypothecate revenues which may be realized by the authority from the operation of any property so conveyed to the authority.

(b) When, in accordance with this article, any county shall activate a hospital authority for such county and such authority shall acquire or construct or shall make preparations to acquire or construct a hospital in the county, any municipality in the county shall be authorized to contract with the hospital authority for the care in such hospital of indigent sick or injured persons who are residents of the municipality either on a per-patient-per-day basis or for a fixed amount of money payable at such time as the contracting parties may agree upon; and any such contract may, at the election of such municipality, be binding upon it for a period of not exceeding 40 years. Such contract and the amount to be received by the hospital authority thereunder may be pledged by the hospital authority as security for the payment of the principal and interest of any bonds or revenue anticipation certificates which it may issue in order to acquire or construct the hospital.