Streptococcus suisSequence Type 7 Outbreak, Sichuan, China

Abstract

An outbreak of Streptococcus suis serotype 2 emerged in the summer of 2005 in Sichuan Province, and sporadic infections occurred in 4 additional provinces of China. In total, 99 S. suis strains were isolated and analyzed in this study: 88 isolates from human patients and 11 from diseased pigs. We defined 98 of 99 isolates as pulse type I by using pulsed-field gel electrophoresis analysis of SmaI-digested chromosomal DNA. Furthermore, multilocus sequence typing classified 97 of 98 members of the pulse type I in the same sequence type (ST), ST-7. Isolates of ST-7 were more toxic to peripheral blood mononuclear cells than ST-1 strains. S. suis ST-7, the causative agent, was a single-locus variant of ST-1 with increased virulence. These findings strongly suggest that ST-7 is an emerging, highly virulent S. suis clone that caused the largest S. suis outbreak ever described.

Isolation and characterization of α-enolase, a novel fibronectin-binding protein from Streptococcus suis

“…Over the past 15 years, S. suis infections have emerged as a major problem for the swine industry worldwide, and it is also considered an important zoonotic agent (Higgins & Gottschalk., 2005;Tang et al, 2006;Ye et al, 2006). The pathogen is able to spread systemically from the nasopharynx, resulting in either general septicaemia or infections of specific organs (e.g.…”

“…S. suis, especially serotype 2, has also been described as an important zoonotic agent that affects people in close contact with infected pigs or pork-derived products (Lun et al, 2007). Indeed, an important number of cases of human disease with a high rate of mortality in China were linked directly to a concurrent outbreak of S. suis infection in pigs (Ye et al, 2006).…”

“…S. suis, especially serotype 2, has also been described as an important zoonotic agent that affects people in close contact with infected pigs or pork-derived products (Lun et al, 2007). Indeed, an important number of cases of human disease with a high rate of mortality in China were linked directly to a concurrent outbreak of S. suis infection in pigs (Ye et al, 2006).Little is known about S. suis virulence factors. The capsule polysaccharide (CPS) is a critical virulence factor, given that unencapsulated isogenic mutants are completely avirulent and rapidly cleared from the circulation in pig and mouse infection models (Charland et al, 2000;Smith et al, 1999).…”

Prevalência de Streptococcus suis sorotipo 2: discussão da literatura brasileira

“…Em julho de 2005 ocorreu o maior surto de infecção humana por S. suis tipo 2 na província de Sichuan, China, com 215 casos reportados e 38 óbitos. Surtos similares aconteceram em outras províncias da China, em 1998 e 1999 (Ye et al, 2006;Lun et al, 2007).…”

Predominance of Streptococcus suis ST1 and ST7 in human cases in China, and detection of a novel sequence type, ST658

“…In addition, bacterial cytotoxicity to Caco-2 cell line was evaluated with Cyto-Tox 96 Cytoxicity Kit (Promega) according to the manufacturer's instructions. Caco-2 was incubated with log-phase strains (multiplicity of infection D 100:1) and kept at 37 C for 4 h. 8 The cytotoxicity levels of LSM102 and P1/7 were 75.5 § 12 .6% and 4.4 § 4.6%, respectively. Results above indicate that LSM102 is highly pathogenic.…”