BACKGROUND/PURPOSE: Little information is available on the differences in 
frequency of pyrogenic exotoxin genes between strains of group A streptococci 
that cause scarlet fever and those that cause pharyngotonsillitis in children in 
Taiwan. This study retrospectively monitored the presence of pyrogenic exotoxin 
genes, the emm typing, and the susceptibility of macrolide drugs in 
Streptococcus pyogenes isolated from children diagnosed with scarlet fever and 
pharyngotonsillitis in northern Taiwan.
MATERIALS AND METHODS: Isolates of S. pyogenes were recovered from children with 
scarlet fever (n = 21) and acute pharyngotonsillitis (n = 29) during 2000-2011. 
The isolates were characterized according to the presence of spe genes and emm 
typing. Antibiograms were determined by the disk diffusion method and agar 
dilution test. Polymerase chain reaction was used to detect the presence of erm 
genes in isolates that showed nonsusceptibility to erythromycin. All isolates 
underwent additional genotyping by pulsed-field gel electrophoresis.
RESULTS: In isolates from patients with scarlet fever, the frequencies of 
pyrogenic exotoxin genes were 9.5% for speA, 81.0% for speB, 4.8% for speC, and 
71.4% for speF. In isolates from patients with pharyngotonsillitis, the 
frequencies were 17.2% for speA, 72.4% for speB, 13.8% for speC, and 69.0% for 
speF. There were no significant differences in frequencies of the exotoxin genes 
between the two groups of isolates. Eight emm sequence types were identified 
from all group A streptococci isolates. The most common types were emm12 
followed by emm1 and emm4. The erythromycin resistant rate was 4/50 (8%). The 
ermB gene was detected in only one isolate from a patient with 
pharyngotonsillitis. Pulsed-field gel electrophoresis had a total of three sets 
of clustered strains, which showed >80% homology and belonged to the same emm 
type.
CONCLUSION: There were no significant differences in frequencies of the spe 
genes between S. pyogenes isolates from patients with scarlet fever and patients 
with pharyngotonsillitis. The most common emm type was emm12. Low erythromycin 
resistance in S. pyogenes was observed.