OREANDA-NEWS. A.M. Best has downgraded the financial strength rating to B++ (Good) from A- (Excellent) and the issuer credit ratings to “bbb” from “a-” of Istmo Compañía de Reaseguros, Inc. (Istmo Re) (Panama City, Panama), Aseguradora del Istmo, S.A. (ADISAP) (Panama City, Panama) and Liffey Reinsurance Company Limited (Liffey Re) (Dublin, Ireland). Additionally, A.M. Best has placed the ratings under review with negative implications.