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LOCAL SPECIFIC THERAPY OF EXPERIMENTAL PNEUMOCOCCAL MENINGITIS : IV. TYPE II PNEUMOCOCCAL MENINGITIS IN DOGS
1Laboratories of The Rockefeller Institute for Medical Research.
Abstract:
1. With properly selected strains of Type II pneumococci, fatal meningitis may be produced by intrathecal infection in dogs. 2. The pathology of the disease differs from that produced by Type I pneumococci, at least with the strains employed. 3. Type II meningitis is characterized by early, very marked reactions, a very heavy fibrin exudation, and a tendency toward the rapid establishment of blocks. 4. Extreme vasodilatation and. hemorrhage are common. 5. The fibrinopurulent exudate tends to involve the walls and perivascular sheaths of deeply penetrating vessels, thereby causing thrombosis. 6. Thrombosis leads to foci of parenchymatous softening which, on subsequent infection, become brain abscesses. 7. The lateral venticles are a "point of election" for the luxuriant growth of pneumococci. Conversely there is evidence that Type II organisms tend somewhat to disappear from other regions, owing either to spontaneous phagocytosis or to filtration into the blood stream. The lateral ventricles, however, continually renew the supply. 8. Hydrocephalus occurs early-sometimes during the 2nd day of the disease. 9. Central myelitis is common and appears early in the disease. 10. Deep nerve cell lesions with necrosis and neuronophagia are encountered. Their pathology suggests a toxic source. 11. In most cases treatment has been impossible owing to severe early reactions, and only as a prophylactic has optochin-serum therapy any real value. It delays death, but has in no instance cured established disease in the dog. 12. Systemic generalization of Type II meningeal infection in the dog occurs, but it is rarely of sufficient extent to modify prognosis.
Insights
Fatal canine meningitis caused by Type II pneumococci shows distinct pathology from Type I, with early reactions, fibrin exudation, and potential brain abscess formation. Treatment efficacy is limited in established cases.
Area of Science:
- Neurology
- Infectious Diseases
- Pathology
Background:
- Meningitis is a serious infection affecting the membranes surrounding the brain and spinal cord.
- Pneumococci are a common cause of bacterial meningitis.
- Understanding the specific pathology of different pneumococcal types is crucial for effective treatment.
Purpose of the Study:
- To investigate the pathological characteristics of Type II pneumococcal meningitis in dogs.
- To compare the pathology of Type II pneumococcal meningitis with that caused by Type I pneumococci.
- To evaluate the potential for treatment in established cases of canine meningitis.
Main Methods:
- Intrathecal infection of dogs with selected strains of Type II pneumococci.
- Detailed pathological examination of affected canine brains and spinal cords.
- Observation of disease progression and response to optochin-serum therapy.
Main Results:
- Type II pneumococcal meningitis in dogs presents with early, severe reactions, significant fibrin exudation, and rapid block formation.
- Pathology includes extreme vasodilatation, hemorrhage, thrombosis leading to brain abscesses, and early hydrocephalus.
- Lateral ventricles are a favored site for pneumococcal growth, while other regions may show clearance.
- Central myelitis and deep nerve cell lesions with neuronophagia are common, suggesting a toxic origin.
- Optochin-serum therapy showed prophylactic value but did not cure established meningitis in dogs.
Conclusions:
- Type II pneumococcal meningitis in dogs has a unique and severe pathological profile.
- The disease progression involves vascular damage, exudate formation, and central nervous system lesions.
- Current therapeutic interventions have limited success in treating established Type II pneumococcal meningitis in this model.
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