Synergistic composition comprising propolis comprising polyphenols at a concentration between 70 and 90% by weight with respect to propolis and carnosic acid, for use thereof for preventing and/or treating infections caused by the species of the opportunistic fungus Cryptococcus neoformans such as cryptococcosis, meningitis and pneumonia in humans and/or in animals, pharmaceutical composition, veterinarian composition and food product related thereto.