The present invention relates to blood coagulation factor XIII (FXIII) for treatment and/or prevention of an infection by a microorganism and/or the symptoms associated with said infection, a pharmaceutical composition comprising a pharmaceutically effective amount of said FXIII, a method for the manufacture of a medicament comprising a pharmaceutically effective amount of said FXIII, and a method of treatment comprising administering to a patient in need a pharmaceutically effective amount of said FXIII.