Cerebral abscesses in a pig: Atypical manifestations of <i>Streptococcus suis </i>serotype 2-induced meningoencephalitis

This article describes the findings associated with Streptococcus suis serotype 2 in a 2.5-month-old mixed-breed male pig. Clinically, the animal demonstrated torticollis, paddling movement, lateral recumbency, and convulsions. Gross evaluation of the brain revealed multiple abscesses, asymmetrically located within the right cerebral hemisphere and in contact with the meningeal surface. Histopathological evaluation revealed multifocal to coalescing cerebral abscesses associated with intralesional bacterial colonies and purulent meningoencephalitis with vasculitis. Biochemical analysis demonstrated that the intralesional bacterium was a gram-positive coccus, with negative reactions to the Voges-Proskauer, catalase, and NaCl assays, and produced acid in trehalose and salicin broths. A polymerase chain reaction assay, using DNA from bacteria cultured from the brain abscesses, amplified the partial 459 base-pair fragment of the capsular gene of S suis serotype 2. The histopathological, microbiological, and molecular findings support a diagnosis of S suis serotype 2-induced cerebral abscesses with meningitis. This case represents an atypical manifestation of streptococcal meningoencephalitis of swine and is, to our knowledge, the first description of S suis serotype 2-induced cerebral abscesses in pigs.