A purified SpA antibody for use in a method of treating or preventing a Staphylococcus infection comprising administering said antibody to a patient having a Staphylococcus infection wherein the purified SpA antibody comprises: (i) six CDRs having sequences of GFAFSNYD (SEQ ID NO: 11), ISSGGTYP (SEQ ID NO: 12), ARGGFLITTRDYYAMDY (SEQ ID NO: 13), SSVSY (SEQ ID NO: 16), DTS (SEQ ID NO: 17) and QQWSSYPPT (SEQ ID NO: 18); (ii) six CDRs having sequences of GYTFTEYS (SEQ ID NO: 21), FYPGSGYI (SEQ ID NO: 22), ARHGYGNYVGYAMDY (SEQ ID NO: 23), EIIYSY (SEQ ID NO: 26), FAK (SEQ ID NO: 27) and QHHYGTPYT (SEQ ID NO: 28); (iii) six CDRs having sequences of GYNFTDYS (SEQ ID NO: 31), INTETAES (SEQ ID NO: 32), AHFDC (SEQ ID NO: 33), QSLVHSNGNTY (SEQ ID NO: 36), KVS (SEQ ID NO: 37) and SQITYVPWT (SEQ ID NO: 38); (iv) six CDRs having sequences of GFTFNTNA (SEQ ID NO:51), IRSKSNNYAT (SEQ ID NO:52), VTEHYDYDYYVMDY (SEQ ID NO:53), ESVEYSGASL (SEQ ID NO:56), AAS (SEQ ID NO:57) and QQSRKVPST (SEQ ID NO:58); (v) six CDRs having sequences of GNAFTNYL (SEQ ID NO:61), INPGSGIT (SEQ ID NO:62), SGSANWFAY (SEQ ID NO:63), ESVEYSGASL (SEQ ID NO:66), AAS (SEQ ID NO:67) and QQSRKVPST (SEQ ID NO:68); (vi) six CDRs having sequences of GNAFTNYL (SEQ ID NO:71), INPGSGIT (SEQ ID NO:72), SGSANWFAY (SEQ ID NO:73), ESVEYSGASL (SEQ ID NO:76), AAS (SEQ ID NO:77) and QQSRKVPST (SEQ ID NO:78); (vii) six CDRs having sequences of GYSFTSYY (SEQ ID NO:81), IDPFNGGT (SEQ ID NO:82), ARYGYDGTFYAMDY (SEQ ID NO:83), SSVSY (SEQ ID NO:86), EIS (SEQ ID NO:87) and QQWSYPFT (SEQ ID NO:88); or (viii) six CDRs having sequences of RFTFSSYV (SEQ ID NO:96), IGSGGTTY (SEQ ID NO:97), RGRGYGFAWYFDV (SEQ ID NO:98), SSVSY (SEQ ID NO:101), DTS (SEQ ID NO:102) and QQWSSYPPT (SEQ ID NO:103); and wherein the purified SpA antibody has an association constant for a SpA KKAA polypeptide of between 0.5 and 100 x 10 9 M -1 as measured by ELISA, wherein the SpA KKAA polypeptide consists of the amino acid sequence of SEQ ID NO: 7. (i) six CDRs having sequences of GFAFSNYD (SEQ ID NO: 11), ISSGGTYP (SEQ ID NO: 12), ARGGFLITTRDYYAMDY (SEQ ID NO: 13), SSVSY (SEQ ID NO: 16), DTS (SEQ ID NO: 17) and QQWSSYPPT (SEQ ID NO: 18); (ii) six CDRs having sequences of GYTFTEYS (SEQ ID NO: 21), FYPGSGYI (SEQ ID NO: 22), ARHGYGNYVGYAMDY (SEQ ID NO: 23), EIIYSY (SEQ ID NO: 26), FAK (SEQ ID NO: 27) and QHHYGTPYT (SEQ ID NO: 28); (iii) six CDRs having sequences of GYNFTDYS (SEQ ID NO: 31), INTETAES (SEQ ID NO: 32), AHFDC (SEQ ID NO: 33), QSLVHSNGNTY (SEQ ID NO: 36), KVS (SEQ ID NO: 37) and SQITYVPWT (SEQ ID NO: 38); (iv) six CDRs having sequences of GFTFNTNA (SEQ ID NO:51), IRSKSNNYAT (SEQ ID NO:52), VTEHYDYDYYVMDY (SEQ ID NO:53), ESVEYSGASL (SEQ ID NO:56), AAS (SEQ ID NO:57) and QQSRKVPST (SEQ ID NO:58); (v) six CDRs having sequences of GNAFTNYL (SEQ ID NO:61), INPGSGIT (SEQ ID NO:62), SGSANWFAY (SEQ ID NO:63), ESVEYSGASL (SEQ ID NO:66), AAS (SEQ ID NO:67) and QQSRKVPST (SEQ ID NO:68); (vi) six CDRs having sequences of GNAFTNYL (SEQ ID NO:71), INPGSGIT (SEQ ID NO:72), SGSANWFAY (SEQ ID NO:73), ESVEYSGASL (SEQ ID NO:76), AAS (SEQ ID NO:77) and QQSRKVPST (SEQ ID NO:78); (vii) six CDRs having sequences of GYSFTSYY (SEQ ID NO:81), IDPFNGGT (SEQ ID NO:82), ARYGYDGTFYAMDY (SEQ ID NO:83), SSVSY (SEQ ID NO:86), EIS (SEQ ID NO:87) and QQWSYPFT (SEQ ID NO:88); or (viii) six CDRs having sequences of RFTFSSYV (SEQ ID NO:96), IGSGGTTY (SEQ ID NO:97), RGRGYGFAWYFDV (SEQ ID NO:98), SSVSY (SEQ ID NO:101), DTS (SEQ ID NO:102) and QQWSSYPPT (SEQ ID NO:103); and