Acquisition of K:1-like antigen during terminal sepsis

This report describes a patient whose own and transfused K:-1 red cell populations became strongly K:1 during a terminal episode of sepsis due to a group D streptococcus organism, Streptococcus faecium. Subsequent in vitro studies using normal K:-1 red cells inoculated with that organism showed that it could render the red cells agglutinable by reagents containing IgG anti-K1. In addition, disrupted S. faecium organisms rendered Jkb-negative red cells agglutinable by those reagents.