Carriage of the zoonotic organism Streptococcus suis in chicken flocks in Vietnam.
Nhung NT., Yen NTP., Cuong N., Kiet BT., Hien VB., Campbell J., Thwaites G., Baker S., Geskus R., Ashton P., Carrique-Mas J.
Streptococcus suis infections are an emerging zoonotic agent causing severe disease in humans and a major pig pathogen worldwide. We investigated the colonization of S. suis in healthy chickens in different flocks (n = 59) as well as in-contact pigs in farms with S. suis-positive chickens (n = 44) in the Mekong Delta of Vietnam. Streptococcus suis was isolated from 20 (33.9%) chicken flocks and from all pigs investigated. Chicken isolates formed a distinct genotypic cluster compared with pig and human strains, although two chicken isolates (10%) clustered with pig isolates. Chicken isolates had unusually high levels of resistance against tetracycline (100%), clindamycin (100%) and erythromycin (95%); and intermediate resistance against penicillin (35%) and ceftriaxone (15%). Our findings suggest that chickens may potentially represent a source of S. suis infection to in-contact humans and pigs.