Misidentification of S. suis as a Zoonotic Agent

BACKGROUND: Streptococcus suis is an emerging zoonotic pathogen. This bacterium commonly causes meningitis in human and is often associated with hearing and vestibular dysfunction. S. suis tends to be misidentified, leading to under-diagnosis. CASE PRESENTATION: A previously healthy 50-year-old man was admitted to one of the district hospitals in Bali Province, Indonesia, due to meningitis. He had a history of consuming homemade raw pork product two days before the onset of illness. Streptococcus mitis was identified from the cerebrospinal fluid culture by using VITEX 2 COMPACT (Biomeriuex) with a 99% probability score. This patient had clinical symptoms and risk factor identical to S. suis infection. Therefore, we performed confirmation tests for the cerebrospinal fluid by PCR (using primer specific for gdh and recN) and sequencing of those PCR products. Both of the confirmation tests showed a positive result for S. suis. CONCLUSION: There are few reports of S. suis infections in Indonesia, but we believe that the cases in Indonesia, especially Bali, are not uncommon. The under-reported cases are perhaps due to the difficulties in differentiating S. suis from other Streptococcus species by culture method, particularly Streptococcus mitis. Therefore, confirmation by PCR is necessary.