Poster Presentation 20th Lancefield International Symposium on Streptococci and Streptococcal Diseases 2017

The prevalence of Streptococcus suis in tiet canh, a traditional raw pig blood dish in Vietnam (#150)

Ha Huynh 1 , Khiem Nguyen 1 , Hoa Ngo 1
  1. Oxford University Clinical Research Unit, District 5, HO CHI MINH CITY, Viet Nam

S. suis is an emerging zoonotic agent capable of causing severe invasive disease in human. As consuming raw port products is the most important risk for human infection in Vietnam, this study was carried out to investigate the existence of viable S. suis cells in tiet canh – a popular raw pig blood dish - and to examine the potential virulence of all isolates and their resistant profile toward critical antimicrobials. A total of 188 tiet canh samples bought from local food shops in 4 cities around Vietnam and prepared at home for traditional family celebrations were collected. The result indicated that 180 (95.7%) were found positive for S. suis of which 124 (65.9%) were positive to S. suis serotype 2. The Ct value ranged from 23 to 39 (median=36), corresponding to the predicted target bacterial load in enriched samples of 1x103 to 21.4x106 (4.4*103) cells/ml. A total of 32 S. suis strains, six of which were serotype 2, were successfully isolated from 29 samples (15.4%). For strain characterization, 21/32 (65.6%) possessed at least 4 virulence factors indicating some level of virulence in causing diseases in human and for the first time, full resistance toward antimicrobials used to treat S. suis in human (penicillin and ceftriaxone) were reported. These findings provide concrete practical evidence confirming tiet canh is a high-risk dish for human S. suis infection and demonstrate the role of raw food as a reservoir of antimicrobial resistant bacteria that can be transferred to and cause diseases in humans.