Evolution and global dissemination of macrolide-resistant group A streptococci

DA Robinson, JA Sutcliffe, W Tewodros… - Antimicrobial agents …, 2006 - Am Soc Microbiol
DA Robinson, JA Sutcliffe, W Tewodros, A Manoharan, DE Bessen
Antimicrobial agents and chemotherapy, 2006Am Soc Microbiol
Macrolide-resistant group A streptococci (MRGAS) have been recovered from many
countries worldwide. However, the strain typing information that is available has been
insufficient for estimating the total number of macrolide-resistant clones, their geographic
distributions, and their evolutionary relationships. In this study, sequence-based strain typing
was used to characterize 212 MRGAS isolates from 34 countries. Evaluation of clonal
complexes, emm type, and resistance gene content [erm (A), erm (B), mef (A), and …
Abstract
Macrolide-resistant group A streptococci (MRGAS) have been recovered from many countries worldwide. However, the strain typing information that is available has been insufficient for estimating the total number of macrolide-resistant clones, their geographic distributions, and their evolutionary relationships. In this study, sequence-based strain typing was used to characterize 212 MRGAS isolates from 34 countries. Evaluation of clonal complexes, emm type, and resistance gene content [erm(A), erm(B), mef(A), and undefined] indicate that macrolide resistance was acquired by GAS organisms via ≥49 independent genetic events. In contrast to other collections of mostly susceptible GAS, genetic diversification of MRGAS clones has occurred primarily by mutation rather than by recombination. Twenty-two MRGAS clonal complexes were recovered from more than one continent; intercontinental strains represent nearly 80% of the MRGAS isolates under study. The findings suggest that horizontal transfer of macrolide resistance genes to numerous genetic backgrounds and global dissemination of resistant clones and their descendants are both major components of the present-day macrolide resistance problem found within this species.
American Society for Microbiology