title: Slaughterhouse pigs are a major reservoir of Streptococcus suis serotype 2 capable of causing human infection in southern Vietnam.
abstract: Streptococcus suis is a pathogen of major economic significance to the swine industry and is increasingly recognized as an emerging zoonotic agent in Asia. In Vietnam, S. suis is the leading cause of bacterial meningitis in adult humans. Zoonotic transmission is most frequently associated with serotype 2 strains and occupational exposure to pigs or consumption of infected pork. To gain insight into the role of pigs for human consumption as a reservoir for zoonotic infection in southern Vietnam, we determined the prevalence and diversity of S. suis carriage in healthy slaughterhouse pigs. Nasopharyngeal tonsils were sampled from pigs at slaughterhouses serving six provinces in southern Vietnam and Ho Chi Minh City area from September 2006 to November 2007. Samples were screened by bacterial culture. Isolates of S. suis were serotyped and characterized by multi locus sequence typing (MLST) and pulse field gel electrophoresis (PFGE). Antibiotic susceptibility profiles and associated genetic resistance determinants, and the presence of putative virulence factors were determined. 41% (222/542) of pigs carried S. suis of one or multiple serotypes. 8% (45/542) carried S. suis serotype 2 which was the most common serotype found (45/317 strains, 14%). 80% of serotype 2 strains belonged to the MLST clonal complex 1,which was previously associated with meningitis cases in Vietnam and outbreaks of severe disease in China in 1998 and 2005. These strains clustered with representative strains isolated from patients with meningitis in PFGE analysis, and showed similar antimicrobial resistance and virulence factor profiles. Slaughterhouse pigs are a major reservoir of S. suis serotype 2 capable of causing human infection in southern Vietnam. Strict hygiene at processing facilities, and health education programs addressing food safety and proper handling of pork should be encouraged.
authors.affiliation: Oxford University Clinical Research Unit, Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam. hoant@oucru.org
authors.forename: Thi Hoa
authors.initials: TH
authors.lastname: Ngo
authors.forename: Thi Bich Chieu
authors.initials: TB
authors.lastname: Tran
authors.forename: Thi Thu Nga
authors.initials: TT
authors.lastname: Tran
authors.forename: Van Dung
authors.initials: VD
authors.lastname: Nguyen
authors.forename: James
authors.initials: J
authors.lastname: Campbell
authors.forename: Hong Anh
authors.initials: HA
authors.lastname: Pham
authors.forename: Huu Tho
authors.initials: HT
authors.lastname: Huynh
authors.forename: Van Vinh Chau
authors.initials: VV
authors.lastname: Nguyen
authors.forename: Juliet E
authors.initials: JE
authors.lastname: Bryant
authors.forename: Tinh Hien
authors.initials: TH
authors.lastname: Tran
authors.forename: Jeremy
authors.initials: J
authors.lastname: Farrar
authors.forename: Constance
authors.initials: C
authors.lastname: Schultsz
mesh_terms: D000003:Abattoirs; D000818:Animals; D004197:Disease Reservoirs / Q000382:microbiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D005843:Geography; D006801:Humans; D014066:Palatine Tonsil / Q000382:microbiology; D012703:Serotyping; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D017011:Streptococcus suis / Q000145:classification* / Q000302:isolation & purification; D034421:Sus scrofa / Q000382:microbiology*; D046509:Tissue Culture Techniques; D014744:Vietnam / Q000453:epidemiology