Pneumococci insensitive to Penicillin

Abstract

PNEUMOCOCCI of all capsular types have been regarded as highly sensitive to penicillin¹ since its introduction for the treatment of human infections in 1940. Although penicillin-insensitive mutants can be selected in vitro by repeated subculture in the presence of sub-inhibitory concentrations of penicillin^2–6, resistant wild strains were not recognized until 1967, when penicillin-insensitive pneumococci (type 23) were isolated from a patient with hypogammaglobulinaemia and bronchiectasis, who had received much antibiotic therapy, including penicillin⁷. We now report further strains of pneumococci, isolated in Australia and New Guinea, relatively insensitive to both penicillin and cephalosporin antibiotics.