Characteristics of Streptococcus pyogenes strains isolated from Chinese children with scarlet fever.
OBJECTIVE
To analyse the characteristics of Streptococcus pyogenes isolates from Chinese children with scarlet fever.


METHODS
Minimal inhibitory concentration with nine antibiotics was performed on 145 Streptococcus pyogenes isolates acquired from Beijing and Shanghai in 2007. Their macrolide-resistant genes (mefA, ermB and ermA- a subclass of ermTR), superantigens (speA and speC), and en-coding mature M protein gene (emm gene) were amplified by PCR.


RESULTS
A total of 97.9% of the isolates exhibited resistance to the macrolides, while 96.6% manifested resistance to tetracycline. All isolates were sensitive to chloramphenicol, penicillin, cefradine, and ofloxacin. Moreover, 94.5% exhibited a cMLSB phenotype, while 90.3% had the ermB gene. Five emm types (emm1.0, emm4.0, emm12.0, emm22.0 and st5240) were discovered, of which 9.7% carried the superantigen speA, 35.9% carried the speC, 42.8% carried both speA and speC and 11.7% carried neither speA nor speC. Finally, 85.5% of emm1.0 and 15.5% of emm12.0 isolates carried speA, while 79.0% of emm1.0 and 75.9% of emm12.0 isolates carried speC.


CONCLUSIONS
The Streptococcus pyogenes isolates had high resistance rates against macrolides and tetracycline. They mainly expressed the ermB gene type and cMLSB phenotype. Their common emm types are emm1.0 and emm12.0, which have different frequencies of speA and speC.
Liang
Yunmei
Y
Beijing Children's Hospital, Affiliated to the Capital Medical University, Beijing, China.
Shen
Xuzhuang
X
Huang
Guoying
G
Wang
Chuanqing
C
Shen
Ying
Y
Yang
Yonghong
Y
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D002515:Cephradine / Q000494:pharmacology; D002648:Child; D002675:Child, Preschool; D002681:China; D002701:Chloramphenicol / Q000494:pharmacology; D002981:Clindamycin / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000187:drug effects* / Q000235:genetics / Q000276:immunology; D006801:Humans; D018942:Macrolides / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods; D015242:Ofloxacin / Q000494:pharmacology; D010406:Penicillins / Q000494:pharmacology; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012541:Scarlet Fever / Q000382:microbiology*; D013297:Streptococcus pyogenes / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D018089:Superantigens / Q000235:genetics; D013754:Tetracyclines / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D018942:Macrolides; D010406:Penicillins; D018089:Superantigens; D013754:Tetracyclines; D002981:Clindamycin; D002701:Chloramphenicol; D015242:Ofloxacin; D002515:Cephradine