Streptococcus suis, an important pig pathogen and emerging zoonotic agent—an update on the worldwide distribution based on serotyping and sequence typing

Abstract

Streptococcus suis is an important pathogen causing economic problems in the pig industry. Moreover, it is a zoonotic agent causing severe infections to people in close contact with infected pigs or pork-derived products. Although considered sporadic in the past, human S. suis infections have been reported during the last 45 years, with two large outbreaks recorded in China. In fact, the number of reported human cases has significantly increased in recent years. In this review, we present the worldwide distribution of serotypes and sequence types (STs), as determined by multilocus sequence typing, for pigs (between 2002 and 2013) and humans (between 1968 and 2013). The methods employed for S. suis identification and typing, the current epidemiological knowledge regarding serotypes and STs and the zoonotic potential of S. suis are discussed. Increased awareness of S. suis in both human and veterinary diagnostic laboratories and further establishment of typing methods will contribute to our knowledge of this pathogen, especially in regions where complete and/or recent data is lacking. More research is required to understand differences in virulence that occur among S. suis strains and if these differences can be associated with specific serotypes or STs.

Streptococcus suis synthesizes deoxyadenosine and adenosine by 5’-nucleotidase to dampen host immune responses

“…S. suis is also recognized as an important zoonotic pathogen for humans in close contact with infected pigs or contaminated pork. Human infection caused by S. suis has been reported in Asia, Europe, South America, North America, and Oceania [2]. At least nine serotypes can cause infection in humans, including serotypes 2, 4, 5, 9, 14, 16, 21, 24, and 31 [2–4].…”

“…Human infection caused by S. suis has been reported in Asia, Europe, South America, North America, and Oceania [2]. At least nine serotypes can cause infection in humans, including serotypes 2, 4, 5, 9, 14, 16, 21, 24, and 31 [2–4]. Moreover, in Vietnam and Thailand, S. suis has been identified as the first and second most common cause of adult meningitis, respectively [5].…”

IgM cleavage by Streptococcus suis reduces IgM bound to the bacterial surface and is a novel complement evasion mechanism

“…These piglets might develop suppurative meningitis, arthritis, endocarditis, serositis and septicemia upon S. suis infection [1]. S. suis is also an emerging zoonotic agent especially in Southeast Asia [4]. …”

“…It has been divided into 35 serotypes and more than 700 sequence types (ST) [5]. Serotype 2 is worldwide the most frequently isolated from diseased pigs and humans [4]. However, other serotypes such as serotypes 9, 7, 3 and 1/2 can cause invasive disease as well.…”

“…However, other serotypes such as serotypes 9, 7, 3 and 1/2 can cause invasive disease as well. The distribution of serotypes depends on the geographical region [4]. However, special adaption to its main host, the pig, is not well understood.…”