MEXICO CITY--(BUSINESS WIRE)--A.M. Best has affirmed the financial strength rating (FSR) of A- (Excellent) and the issuer credit rating (ICR) of “a-” of Istmo Compania de Reaseguros, Inc. (Istmo Re) (Panama City, Panama), Del Istmo Assurance Corp. (Del Istmo Assurance) (Panama City, Panama) and Liffey Reinsurance Company Limited (Liffey Re) (Dublin, Ireland). The outlook for all ratings is stable. Istmo Re’s ratings reflect its solid capitalization levels with a strong reinsurance program and g