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Journal of Clinical Microbiology, October 2009, p. 3161-3169, Vol. 47, No. 10
0095-1137/09/$08.00+0     doi:10.1128/JCM.00202-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

emm1/Sequence Type 28 Strains of Group A Streptococci That Express covR at Early Stationary Phase Are Associated with Increased Growth and Earlier SpeB Secretion{triangledown}

Chuan Chiang-Ni,1 Po-Xing Zheng,2 Yueh-Ren Ho,1 Hsiu-Mei Wu,2 Woei-Jer Chuang,3 Yee-Shin Lin,4 Ming-T. Lin,5 Ching-Chuan Liu,6 and Jiunn-Jong Wu1,2*

Institute of Basic Medical Sciences,1 Departments of Medical Laboratory Science and Biotechnology,2 Biochemistry,3 Microbiology and Immunology,4 Pediatrics, College of Medicine, National Cheng Kung University, Tainan, Taiwan,6 Department of Biochemistry, College of Medicine, Tzu Chi University, Hualien, Taiwan5

Received 30 January 2009/ Returned for modification 20 May 2009/ Accepted 17 August 2009

Streptococcus pyogenes (group A streptococcus [GAS]) is a versatile human pathogen, and emm1/sequence type 28 (ST28) is the most frequently isolated type from GAS infections. The emm1/ST28 strain is associated with necrotizing fasciitis and streptococcal toxic shock syndrome. Growth-phase regulation is one of the important regulatory mechanisms in GAS, which controls gene expression at restricted phases of growth. CovRS, a two-component regulatory system, is considered the regulator of streptococcal pyrogenic exotoxin B (SpeB) and is thought to be activated in the exponential phase of growth. In the present study, Northern hybridization analysis showed that 52% of the analyzed GAS strains expressed covR at the exponential phase, but 48% of the strains expressed covR at the early stationary phase of growth. Strains transcribing covR at the early stationary phase showed better growth and earlier SpeB expression than the other group of strains. Multilocus sequence typing and pulsed-field gel electrophoresis analysis showed only emm1/ST28 strains (which comprise a clonal cluster) were expressing covR at the early stationary phase of growth, indicating that emm1/ST28 strains have special characteristics which may be related to their worldwide distribution.

* Corresponding author. Mailing address: Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, No. 1 Ta-Hsueh Road, Tainan, Taiwan 70101. Phone: 886-6-2353535, ext. 5775. Fax: 886-6-2363956. E-mail: jjwu{at}mail.ncku.edu.tw

{triangledown} Published ahead of print on 26 August 2009.

Journal of Clinical Microbiology, October 2009, p. 3161-3169, Vol. 47, No. 10
0095-1137/09/$08.00+0     doi:10.1128/JCM.00202-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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