Streptococcus suis

Taxobox
name = "Streptococcus suis"
regnum = Bacteria
phylum = Firmicutes
classis = Bacilli
ordo = Lactobacillales
familia = Streptococcaceae
genus = "Streptococcus"
species = "S. suis"
binomial = "Streptococcus suis"
binomial_authority = (ex Elliot 1966)
Kilpper-Bälz & Schleifer 1987

"Streptococcus suis" is spherical, Gram-positive bacterium, and an important pathogen of pigs. Endemic in nearly all countries with an extensive pig industry, "S. suis" is also a zoonotic disease, capable of transmission to humans from pigs.cite journal | author=Sriskandan S, Slater JD | title=Invasive Disease and Toxic Shock due to Zoonotic "Streptococcus suis": An Emerging Infection in the East? | journal=PLoS Med | year=2006 | pages=e187 | volume=3 | issue=5 | pmid=16594733 [http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0030187 fulltext] | doi=10.1371/journal.pmed.0030187] Humans can be infected with "S. suis" when they handle infected pig carcasses or meat, especially with exposed cuts and abrasions on their hands. Human infection can be severe, with meningitis, septicaemia, endocarditis, and deafness as possible outcomes of infection.cite journal | author=Huang YT, Teng LJ, Ho SW, Hsueh PR | title=Streptococcus suis infection | journal=J Microbiol Immunol Infect | year=2005 | pages=306–13 | volume=38 | issue=5 | pmid=16211137] Fatal cases of "S. suis" are uncommon, but not unknown.

Penicillin is the most common antibiotic used in treatment of "S. suis" infection; in cases with cardiac involvement (endocarditis), gentamicin should also be given for synergistic effect.

Zoonotic outbreaks

In July 2005, an outbreak of the disease in humans was reported in Sichuan, China, with higher than usual human morbidity and mortality; over 100 cases and more than 20 deaths were initially reported. Prior to this outbreak, less than 200 total human cases had been reported, and mortality was assumed to be less than 10%. Details of this outbreak and a similar earlier outbreak, also in Sichuan province, have recently been published.cite journal | author=Tang J, "et al". | title=Streptococcal Toxic Shock Syndrome Caused by "Streptococcus suis" Serotype 2 | journal=PLoS Med | year=2006 | pages=e151 | volume=3 | issue=5 | pmid=16584289 | doi=10.1371/journal.pmed.0030151 ]

A total of 204 human cases were documented during the Sichuan outbreak, with 38 fatalities. The human outbreak co-incided with one in the local pig populations. There was no evidence of human-to-human transmission; all of the patients had been in direct contact with pigs. Many of the patients, and almost all of the fatal cases, had typical symptoms of Streptococcal toxic shock syndrome (STSS). To date, STSS has only been documented in patients infected with "S. pyogenes", another member of the Streptococcus family but very different from "S. suis". However, the bacteria isolates from the human and pig samples were clearly "S. suis", and those isolates were able cause typical "S. suis" disease in piglets. The genome of "S. suis" isolates from the outbreak were examined to see whether its DNA sequence could explain why these particular bacteria were able to cause STSS. However, none of the genes that are present in "S. pyogenes" and thought to cause STSS were detected in the "S. suis" isolates. Comparison with other "S. suis" isolates from around the world, including one from an earlier smaller "S. suis" outbreak in Sichuan province that killed 14 out of 25 reported human cases, revealed that the two Chinese isolates were more similar to each other than to any other strains.

Additional experiments are necessary to determine whether the size and high mortality of the recent outbreak is because the Chinese "S. suis" version is more virulent than other strains or due to the circumstances under which the Chinese patients got infected and treated. Studies are under way to characterize the bacterial isolates from the outbreak in detail. Physicians around the world should be aware of the possibility of "S. suis"-associated STSS when they see patients with unexplained sepsis who had been in contact with pigs.

Streptococcus suis has also been identified as the most common cause of meningitis in Vietnam [cite journal|author=Mai NTH, Hoa NT, Nga TVT, "et al."|title="Streptococcus suis" meningitis in adults in Vietnam|year=2008|journal=Clin Infect Dis|volume=46|issue=5|pages=659–667|doi=10.1086/527385] .

References

External links

* [http://news.bbc.co.uk/2/hi/asia-pacific/4720715.stm BBC news report]
* [http://news.yahoo.com/news?tmpl=story&u=/afp/20050730/wl_afp/healthchinadisease_050730194041 AFP news report]
* [http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0030187 PloS Medicine Perspective Article]