Epidemiology and Infection

Original Papers

Streptococci

Characterization of emm types and superantigens of Streptococcus pyogenes isolates from children during two sampling periods

Y. MAa1, Y. YANGa1, M. HUANGa2, Y. WANGa3, Y. CHENa4, L. DENGa5, S. YUa1, Q. DENGa5, H. ZHANGa2, C. WANGa3, L. LIUa4 and X. SHENa1 c1

a1 Beijing Children's Hospital, Affiliated to Capital Medical University, Beijing, China

a2 Shanghai Children's Hospital, Affiliated to Shanghai Jiao Tong University, Shanghai, China

a3 The Fudan University Children's Hospital, Shanghai, China

a4 Chongqing Children's Hospital Affiliated to Chongqing Medical University, Chongqing, China

a5 Guangzhou Children's Hospital, Guangzhou, China

SUMMARY

The characteristics of 359 group A streptococcal (GAS) isolates collected from Chinese paediatric patients in two periods (1993–1994, 2005–2006) were studied. Isolates were assigned to emm types and assayed for eight superantigen (SAg) genes (speA, speC, speH, speI, speG, speJ, ssa, SMEZ). Types emm1 and emm12 were consistently the most prevalent during the two periods, while others varied in frequency. GAS isolates carrying six or more SAg genes increased from 46·53% (1993–1994) to 78·39% (2005–2006); ssa, speH and speJ genes (P<0·05) increased but speA declined (P<0·05). SAg gene profiles were closely associated with the emm type, but strains of the same emm type sometimes carried different SAg genes in the two periods. No significant difference in emm-type distribution and SAg gene profile was noted between isolates from different diseases. These data may contribute towards the development of a GAS vaccine in China.

(Accepted January 14 2009)

(Online publication February 26 2009)

Correspondence:

c1 Author for correspondence: Professor X. Shen, Beijing Children's Hospital, affiliated to Capital Medical University, 56 South Lishi Road, Beijing 100045, P.R. China. (Email: lingyao2008@126.com)

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