Vaccines for pathogens usually target strain-specific surface antigens or toxins, and rarely is there broad antigenic specificity extending across multiple species. Protective antibodies for bacteria are usually specific for surface or capsular antigens. -(136)-Poly-N-acetyl-D-glucosamine (PNAG) is a surface polysaccharide produced by many pathogens, including Staphylococcus aureus, Escherichia coli, Yersinia pestis, Bordetella pertussis, Acinetobacter baumannii, and others. Protective antibodies to PNAG are elicited when a deacetylated glycoform (deacetylated PNAG [dPNAG]; <30% acetate) is used in conjugate vaccines, whereas highly acetylated PNAG does not induce such antibodies. Chemical derivation of dPNAG from native PNAG is imprecise, so we synthesized both -(136)-D-glucosamine (GlcNH 2 ) and -(136)-D-N-acetylglucosamine (GlcNAc) oligosaccharides with linkers on the reducing termini that could be activated to produce sulfhydryl groups for conjugation to bromoacetyl groups introduced onto carrier proteins. Synthetic 5-mer GlcNH 2 (5GlcNH 2 ) or 9GlcNH 2 conjugated to tetanus toxoid (TT) elicited mouse antibodies that mediated opsonic killing of multiple S. aureus strains, while the antibodies that were produced in response to 5GlcNAc-or 9GlcNAc-TT did not mediate opsonic killing. Rabbit antibodies to 9GlcNH 2 -TT bound to PNAG and dPNAG antigens, mediated killing of S. aureus and E. coli, and protected against S. aureus skin abscesses and lethal E. coli peritonitis.