Contamination of Streptococcus suis in pork and edible pig organs in central Thailand

BACKGROUND AND AIM: Streptococcus suis is an important zoonotic pathogen that can cause serious diseases in both swine and humans worldwide, especially in Asian countries. Since the majority of human cases reported in Thailand were infected by the consumption of a raw pork dish, the microbial food safety hazard associated with raw meat has been a matter of concern. Therefore, this study aimed to investigate the contamination by S. suis in pork and edible pig organs sold in central Thailand. MATERIALS AND METHODS: In total, 88 raw pork and pig organ samples were purchased from markets, butcher shops, and supermarkets in central Thailand. The samples were examined using the loop-mediated isothermal amplification (LAMP) technique. LAMP reactions used for the detection of the DNA of S. suis (LAMP(SS)) and S. suis serotype 2 or 1/2 (LAMP(SS2)) were carried out according to previous studies. RESULTS: The percentage of LAMP(SS)-positive samples was as high as 85.23% (75/88) while the percentage of LAMP(SS2)-positive samples was 17.05% (15/88). The percentages of LAMP(SS)- and LAMP(SS2)-positive samples were relatively high in both pig organs (lung and heart) and meat (sliced pork and minced pork) compared with the previous report. Except one supermarket, LAMP(SS)-positive samples were found in all sources investigated in this study. The pork and pig organs obtained from the markets and the butcher shops additionally gave positive results for LAMP(SS2). CONCLUSION: Using LAMP techniques, high rate contamination of S. suis was found in raw pork and edible pig organs sold at different sources in central Thailand. The cross-contamination could have occurred through slaughtering, meat cutting, and meat handling processes. Therefore, consumers and people involved in the pig production industry should be aware of the potential hazards of S. suis infection; food safety education is crucial to prevent further infection.