The present invention relates to antibody molecules that bind to Wall Teichoic Acid (WTA) or Capsular Polysaccharides (CP) such as Capsular Polysaccharides type 5 (CP5). The invention relates in particular to antibody molecules of the IgG isotype having a mutation in the Fc domain that enhances clustering of IgG molecules after target binding. The invention also relates to pharmaceutical compositions containing these molecules and the treatment of infectious diseases using these compositions