CENTENNIAL (S&P Global Ratings) Dec. 2, 2021--S&P Global Ratings revised its outlook to negative from stable and affirmed its 'AA' long-term rating on Chester County Health&Education Facilities Authority, Pa.'s outstanding bonds, issued for Main Line Health System (MLH). MLH is the parent company of Main Line Health. "The outlook revision reflects our view of MLH's unfavorable operating performance that is inconsistent with peers at the current rating level," said S&P Global Ratings credit analyst Alexander Nolan. The health system generated an operating loss through the fiscal 2022 interim period ended Sept. 30, 2021, due to elevated staffing and supply costs as well as higher length of stay and throughput challenges. Latest expectations from management indicate that operations could