Abstract
A 2-year-old male cynomolgus monkey (Macaca fascicularis) showed neurological symptoms during quarantine for importation into Japan, and was euthanized due to poor prognosis. Gross anatomical examination revealed a hemorrhagic lesion around the lateral ventricle in the cerebrum. Histologically, severe diffused suppurative meningitis and ventriculitis were detected with numerous Gram-negative bacilli in the cerebrum. Immunohistochemically, the bacilli were positively stained with an antibody against Klebsiella pneumoniae. The bacterium was isolated from the liver, and it was confirmed to be K. pneumoniae by 16S rDNA sequencing. The isolate displayed a hypermucoviscosity phenotype, was positive for the rmpA and k2A genes, and demonstrated multidrug resistance. These results suggest that invasive K. pneumoniae can cause septicemic infection, characterized by severe diffused suppurative meningoencephalitis in monkeys.