Streptococcus suis, an emerging zoonotic pathogen, causes invasive infections in persons who are in close contact with infected pigs or contaminated pork‐derived products. Although serotype 2 is the most prevalent type in S. suis infections in humans, to the best of our knowledge no human case caused by an unencapsulated strain has been reported previously.
Case presentation:
A 53‐year‐old male alcohol misuser with liver cirrhosis was admitted with sepsis to a hospital in Sukhothai Province, Thailand. He had consumed a homemade raw pork product 3 days prior to the onset of illness. An isolate from blood culture was confirmed as S. suis by species‐specific PCR and 16S rRNA gene sequencing, and as untypeable by a coagglutination test. The absence of a capsule around the bacterial cells was also confirmed by transmission electron microscopy. The isolate was also confirmed as sequence type 28 by sequence typing, and analysis of the capsule locus detected disruption of the cpsE–cpsK region, which comprises an approximately 2.5 kb fragment that contains phosphatase and kinase genes.
Conclusion:
We have identified the first human S. suis infection caused by an unencapsulated strain in a patient with liver cirrhosis. This unencapsulated strain was attributable to a mutation of the cps gene. Clinicians should be aware of the emergence of S. suis infection caused by unencapsulated strains, especially in patients with liver cirrhosis.
BengaL.,
GoetheR.,
RohdeM.,
Valentin‐WeigandP.(2004). Non‐encapsulated strains reveal novel insights in invasion and survival of Streptococcus suis in epithelial cells. Cell Microbiol 6:867–881[CrossRef]
BengaL.,
FuldeM.,
NeisC.,
GoetheR.,
Valentin‐WeigandP.(2008). Polysaccharide capsule and suilysin contribute to extracellular survival of Streptococcus suis co‐cultivated with primary porcine phagocytes. Vet Microbiol 132:211–219[CrossRef]
BrousseauR.,
HillJ.E.,
PrefontaineG.,
GohS.H.,
HareJ.,
HemmingsenS.M.(2001).Streptococcus suis serotypes characterized by analysis of chaperonin 60 gene sequences. Appl Environ Microbiol 67:4828–4833[CrossRef]
BonifaitL.,
GottschalkM.,
GrenierD.(2010). Cell surface characteristics of non‐typeable isolates of Streptococcus suis
. FEMS Microbiol Lett 311:160–166[CrossRef]
de MooreC.E.(1963). Septicaemic infections in pigs, caused by haemolytic streptococci of new Lancefield groups designated R, S and T. Antonie van Leeuwenhoek 27:272–280[CrossRef]
FittipaldiN.,
SeguraM.,
GrenierD.,
GottschalkM.(2012). Virulence factors involved in the pathogenesis of the infection caused by the swine pathogen and zoonotic agent Streptococcus suis
. Future Microbiol 7:259–279[CrossRef]
GottschalkM.,
HigginsR.,
JacquesM.,
DubreuilD.(1992). Production and characterization of two Streptococcus suis capsular type 2 mutants. Vet Microbiol 30:59–71[CrossRef]
GottschalkM.,
HigginsR.,
BoudreauM.(1993). Use of polyvalent coagglutination reagents for serotyping of Streptococcus suis
. J Clin Microbiol 31:2192–2194
GottschalkM.,
XuJ.,
CalzasC.,
SeguraM.(2010).Streptococcus suis: a new emerging or an old neglected zoonotic pathogen?. Future Microbiol 5:371–391[CrossRef]
HillJ.E.,
GottschalkM.,
BrousseauR.,
HarelJ.,
HemmingsenS.M.,
GohS.H.(2005). Biochemical analysis, cpn60 and 16S rDNA sequence data indicate that Streptococcus suis serotype 32 and 34 isolated from pigs, are Streptococcus orisratti.
. Vet Microbiol 107:63–69[CrossRef]
KerdsinA.,
OishiK.,
SripakdeeS.,
BoonkerdN.,
PolwichaiP.,
NakamuraS.,
UchidaR.,
SawanpanyalertP.,
DejsirilertS.(2009). Clonal dissemination of human isolates of Streptococcus suis serotype 14 in Thailand. J Med Microbiol 58:1508–1513[CrossRef]
KerdsinA.,
DejsirilertS.,
PuangpatraP.,
SripakdeeS.,
ChumlaK.,
BoonkerdN.,
PolwichaiP.,
TanimuraS.,
TakeuchiD.other authors(2011a). Genotypic profile of Streptococcus suis serotype 2 and clinical features of infection in humans, Thailand. Emerg Infect Dis 17:835–842[CrossRef]
LakkitjaroenN.,
TakamatsuD.,
OkuraM.,
SatoM.,
OsakiM.,
SekizakiT.(2011). Loss of capsule among Streptococcus suis isolates from porcine endocarditis and its biological significance. J Med Microbiol 60:1669–1676[CrossRef]
NghiaH.D.,
HoaN.T.,
Linhle D.,
CampbellJ.,
DiepT.S.,
ChauN.V.,
MaiN.T.,
HienT.T.,
SprattB.other authors(2008). Human case of Streptococcus suis serotype 16 infection. Emerg Infect Dis 14:155–157[CrossRef]
OkuraM.,
TakamatsuD.,
MaruyamaF.,
NozawaT.,
NakagawaI.,
OsakiM.,
SekizakiT.,
GottschalkM.,
KumagaiY.,
HamadaS.(2013). Genetic analysis of capsular polysaccharide synthesis gene clusters from all serotypes of Streptococcus suis: potential mechanisms for generation of capsular variation. Appl Environ Microbiol 79:2796–2806[CrossRef]
SeguraM.,
VanierG.,
Al‐NumaniD.,
LacoutureS.,
OlivierM.,
GottschalkM.(2006). Proinflammatory cytokine and chemokine modulation by Streptococcus suis in a whole‐blood culture system. FEMS Immunol Med Microbiol 47:92–106[CrossRef]
SmithH.E.,
DammanM.,
van der VeldeJ.,
WagenaarF.,
WisselinkH.J.,
Stockhofe‐ZurwiedenN.,
SmitsM.A.(1999a). Identification and characterization of the cps locus of Streptococcus suis serotype 2: the capsule protects against phagocytosis and is an important virulence factor. Infect Immun 67:1750–1756
SmithH.E.,
VeenbergenV.,
van der VeldeJ.,
DammanM.,
WisselinkH.J.,
SmitsM.A.(1999b). The cps gene of Streptococcus suis serotype 1, 2 and 9: development of rapid serotype‐specific PCR assays. J Clin Microbiol 37:3146–3152
TakeuchiD.,
KerdsinA.,
PienpringamA.,
LoetthongP.,
SamercheaS.,
LuangsukP.,
KhamisraK.,
WongwanN.,
AreeratanaP.other authors(2012). Population‐based study of Streptococcus suis infection in humans in Phayao Province in northern Thailand. PLoS One 7:e31265[CrossRef]
TanabeS.,
BonifaitL.,
FittipaldiN.,
GrignonL.,
GottschalkM.,
GrenierD.(2010). Pleiotropic effects of polysaccharide capsule loss on selected biological properties of Streptococcus suis
. Can J Vet Res 74:65–70