Editor: Craig Shoemaker
Dissemination of streptococcal pyrogenic exotoxin G (spegg) with an IS-like element in fish isolates of Streptococcus dysgalactiae
Article first published online: 25 MAY 2010
© 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved
FEMS Microbiology Letters
Volume 309, Issue 1, pages 105–113, August 2010
How to Cite
Abdelsalam, M., Chen, S.-C. and Yoshida, T. (2010), Dissemination of streptococcal pyrogenic exotoxin G (spegg) with an IS-like element in fish isolates of Streptococcus dysgalactiae. FEMS Microbiology Letters, 309: 105–113. doi: 10.1111/j.1574-6968.2010.02024.x
- Issue published online: 2 JUL 2010
- Article first published online: 25 MAY 2010
- Received 22 February 2010; revised 13 May 2010; accepted 17 May 2010.Final version published online 7 June 2010.
- streptococcal pyrogenic exotoxin G (spegg);
- streptolysin S (sagA);
- insertion sequence
The Lancefield group C α-hemolytic Streptococcus dysgalactiae ssp. dysgalactiae (GCSD) causes systemic granulomatous inflammatory disease and high mortality rates in infected fish. Superantigen and streptolysin S genes are the most important virulence factors contributing to an invasive streptococcal infection. PCR amplification revealed that all strains isolated from moribund fish harbored the streptolysin S structural gene (sagA). GCSD fish isolates were PCR negative for emm, speA, speB, speC, speM, smeZ, and ssa. However, the size of the streptococcal pyrogenic exotoxin G (spegg) locus, a superantigen, in positive S. dysgalactiae fish and pig strains was variable. The ORF of the spegg locus of 26 GCSD fish strains and one GCSD pig strain was inserted with IS981SC. Interestingly, the ORF of the spegg locus of two fish strains of GCSD collected in Malaysia was inserted with an IS981SC–IS1161 hybrid IS element. The hybrid IS element was found in all of the GCSD fish isolates and one GCSD pig through PCR screening. Although no insertion sequence (IS) was detected in the spegg locus of S. dysgalactiae ssp. equisimilis (GCSE) strains, a five-nucleotide deletion mutation was detected in the ORF of the spegg locus of one GCSE strain at the supposed site of IS981SC insertion, resulting in a frameshift mutation.