The present invention encompasses protective monoclonal antibodies that bind to peptidoglycan of Gram-positive bacteria. The antibodies also bind to whole bacteria and enhance phagocytosis and killing of the bacteria in vitro and block nasal colonization by Gram-positive bacteria in vivo. The invention also provides human, humanized and chimeric antibodies. The invention also sets forth the heavy chain and light chain variable regions of an antibody within the invention.