Antibiotic

Antibiotic is an achievement/trophy in Metro Last Light, Metro Last Light Redux and Metro Exodus awarded to the player for killing a certain amount of mutants.

Metro Last Light & Redux
In order to receive this achievements, one has to kill 100 mutants. The player will likely unlock this achievement on their first playthrough. Small, non-hostile mutants, such as Mutant Crows and Shrimp Hatchlings as well as mutants in downloadable content do not count towards the achievement.

Metro Exodus
In Metro Exodus, the required number of kills has been increased to 300 mutants, given the fact that the game is longer and features open environments. Same as before, small, non-hostile mutants, such as Mutant Crows and Shrimp Hatchlings do not count towards the achievement, neither do mutated plants.