In US Veterans, polymicrobial infections had notably worse perioperative outcomes but similar long-term outcomes in comparison to monomicrobial infections. GNR infections were associated with increased long-term mortality. Enterococcus and resistant organisms were associated with increased long-term risk of MI. Polymicrobial infections were associated with greater risk of perioperative complications, including prolonged mechanical ventilation, tracheostomy, and prolonged ICU stay.