An isolated monoclonal antibody or antigen-binding fragment thereof binds to F. tularensis lipopolysaccharide (Ft LPS). The antibody preferably lacks an Fc region or has an impaired Fc-region. The antibody may be formulated into a pharmaceutical composition along with a pharmaceutically acceptable carrier, excipient or diluent. It may be provided in a kit with means for detection of the antibody and instructions for use. A therapeutically effective amount of such an antibody can be used for prophylaxis, treatment or amelioration of Ft infection and for inhibiting Ft uptake by cells in a subject. The antibody can also be used to detect Ft infection. Also disclosed is an isolated nucleic acid molecule encoding the antibody, an expression vector having the isolated nucleic acid molecule, and a host cell transfected with such an expression vector.