A GLOBAL GENE POOL FOR HIGH-LEVEL CEPHALOSPORIN RESISTANCE IN COMMENSAL STREPTOCOCCUS SPECIES AND STREPTOCOCCUS-PNEUMONIAE

Highly penicillin-and cephalosporin-resistant Streptococcus mitis and Streptococcus oralis were isolated in Spain, Hungary, and Berlin. With chromosomal DNA of these strains, resistant transformants of Streptoc occus pneumoniae were obtained that expressed low-affinity variants of penicillin-binding proteins (PBPs) 2x, 1a, 2a, and 2b in different co mbinations, depending on the selective conditions. The transformants h ad cefotaxime MICs of up to 6 mu g/mL, and those with a low-affinity P BP 2b were highly deficient in penicillin-induced lysis. Sequence anal ysis of the pbp2x genes confirmed the presence of a global gene pool o f penicillin resistance determinants shared by commensal and pathogeni c streptococci.