Molecular epidemiology of group A streptococcus causing scarlet fever in northern Taiwan, 2001-2002.

In this study, 830 Streptococcus pyogenes isolates collected between 2001 and 2002 from patients with scarlet fever in northern Taiwan were analyzed by M protein gene (emm) sequence typing, pulsed-field gel electrophoresis (PFGE), and antimicrobial susceptibility testing. A total of 21 emm types and 56 PFGE patterns were identified. The most frequent emm types were emm1 (29.2%), emm4 (24.1%), emm12 (19.0%), emm6 (15.8%), stIL103 (5.7%), and emm22 (1.9%). Antimicrobial resistance profiles were determined, and resistance to erythromycin (24.6%), clindamycin (2.0%), and chloramphenicol (1.3%) was detected. Five major emm types (emm4, emm12, emm1, emm22, and emm6) accounted for 95.6% of the erythromycin-resistant isolates. The decreased prevalence of erythromycin-resistant emm12 strains coincided with the overall decrease in erythromycin resistance from 32.1% in 2001 to 21.1% in 2002 in Taiwan. Five major clones (emm4/2000, emm12/0000, emm4/2010, emm1/1000, and emm22/8100) represented 72.1% of the erythromycin-resistant isolates. The survey of group A Streptococcus emm types, genetic diversity, and antibiotic resistance has direct relevance to current antimicrobial use policies and potential vaccine development strategies.