<prompt> Pneumococcal resistance to penicillin G is mainly acquired by :ConjugationTransductionTransformationAll of the above  <response>: Acquisition of antibiotic resistance by Transduction is common in Staphylococcal and that of by Transformation in Pneumococcus and Neisseria.Vancomycin resistance in enterococci and Staphylococcus is mediated by the conjugative plasmid. 