Streptococcus suis is an important zoonotic pathogen that causes severe human infections, including meningitis and septicemia. It is primarily transmitted through contact with infected pigs or contaminated pork products. Conventional diagnostic methods, such as bacterial culture and PCR, are limited by cost and infrastructure requirements. Loop-mediated isothermal amplification (LAMP) provides a rapid, specific, and equipment-light alternative; however, the instability of liquid-phase reagents necessitates cold-chain storage, limiting field deployment. In this study, we developed and evaluated a colorimetric lyophilized LAMP assay for the detection of S. suis and S. suis serotype 2. The assay, performed at 65 °C for 60 minutes, utilized a pH-sensitive dye enabling visual discrimination of amplification. The lyophilized formulation exhibited high analytical sensitivity and specificity, with no cross-reactivity observed against 12 clinically relevant bacterial species. Stability studies revealed that the freeze-dried reagents retained functionality for at least 30 days at ambient temperature and up to 180 days at 4 °C. Diagnostic performance was further validated using 111 raw pork samples. These findings demonstrate that the lyophilized LAMP assay provides a robust, rapid, and storage-stable amplification tool for S. suis and S. suis serotype 2 detection, suitable for implementation in low-resource or remote settings lacking cold-chain infrastructure.
Khamai et al. (Mon,) studied this question.