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Pathogenesis of meningitis caused by Streptococcus suis type 2
1Department of Clinical Veterinary Medicine, University of Cambridge, United Kingdom.
The Journal of Infectious Diseases
|August 1, 1990
Summary
Streptococcus suis type 2 invades the brain via monocytes migrating through the choroid plexus, causing meningitis. This study details the choroid plexus lesions and bacterial presence within monocytes in pigs.
Area of Science:
- Veterinary Pathology
- Microbiology
- Neuroscience
Background:
- Streptococcus suis type 2 is a significant swine pathogen causing meningitis.
- The precise mechanisms of Streptococcus suis type 2 entry into the central nervous system (CNS) remain incompletely understood.
Purpose of the Study:
- To investigate the pathological changes in the porcine neuraxis following experimental Streptococcus suis type 2 infection.
- To elucidate the role of monocytes in the transport of bacteria into the cerebrospinal fluid (CSF).
Main Methods:
- Histologic and scanning electron microscopic examination of 26 pigs inoculated with Streptococcus suis type 2.
- Demonstration of intracellular bacteria within various tissues and blood cells.
- Tracking of monocyte migration into the CSF.
Main Results:
- All pigs exhibited characteristic lesions in the choroid plexus, including brush border disruption and inflammatory exudate.
- No vasculitis was observed in the cerebral or choroid plexus endothelium.
- Intracellular Streptococcus suis type 2 was found in choroid plexus parenchyma, ventricular exudate, and peripheral blood monocytes.
- Circulating monocytes carrying bacteria-like particles were observed migrating into the CSF.
Conclusions:
- The choroid plexus is a primary site for bacterial entry into the CSF via migrating monocytes.
- Monocyte-associated bacterial transport is a key mechanism in Streptococcus suis type 2 meningitis pathogenesis.
- This supports the concept of monocytes facilitating bacterial access to the CNS through normal cellular pathways.