Public Awareness and Molecular Characterization of Streptococcus suis in a High-Incidence Region of Thailand.

Streptococcus suis is a major zoonotic pathogen, with increasing human cases in Nakhon Ratchasima Province, northeastern Thailand. This study aimed to assess residents' knowledge, attitudes, and practices (KAP) regarding infection risk and to characterize S. suis isolates from pigs. A structured questionnaire was administered to 500 residents to evaluate awareness and behaviors related to S. suis infection. Nasopharyngeal swabs were collected from slaughtered pigs at three slaughterhouses in Nakhon Ratchasima Province. Presumptive Streptococcus isolates were confirmed as S. suis by PCR and further characterized by molecular serotyping, virulence-associated gene profiling, and multilocus sequence typing (MLST). Among residents, mean scores suggested generally high levels of KAP; however, misunderstandings regarding transmission persisted. Residents expressed strong readiness to reduce infection risk. Of 285 pig samples, 122 (42.8%) were positive for S. suis, representing 16 serotypes. Serotype 9 (10.3%) predominated with several serotypes that have been reported in human infections. The predominant virulence-associated gene profile was mrp-/sly-/epf- (77.4%). MLST identified eight STs with five novel STs (ST3147-3151), indicating substantial genetic diversity. Persistent misconceptions despite generally acceptable KAP levels highlight the need for targeted public health education. The high prevalence and genetic variability of S. suis in pigs support ongoing surveillance to monitor potentially pathogenic strains.