Infections of the nervous system are rare but life-threatening complications of systemic infections. The central nervous system (CNS) presents a special milieu for bacterial, fungal, viral and parasitic infections: the brain and spinal cord are protected by bone and meningeal coverings that compartmentalize infection; they are divided by barriers from the systemic circulation; they lack an intrinsic immune system; and they have a unique compact structure. The space between cells in the brain parenchyma is too small to permit passage even of a virus. However, tetanus toxin and some viruses travel through the CNS by axoplasmic flow.
For Meningitis disease, major bacterial causes are Haemophilus influenzae, Streptococcus pneumoniae, and Neisseria meningitidis. Major viral causes are enteroviruses, mumps virus and lymphocytic choriomeningitis virus. Many viruses cause mild meningoencephalitis; herpes simplex viruses and arboviruses are the major causes of potentially fatal disease. Parasitic infections such as malaria, amebiasis with free-swimming amoebas and trichinosis can produce acute encephalopathy or meningitis. Others are associated with chronic disease, such as the chronic sleeping sickness of African trypanosomiasis, the chronic cerebral granulomas caused by Schistosoma japonicum, or abscesses caused by Toxoplasma gondii in immunodeficient patients.
The intracranial infection model is to use infection methods to cause a certain degree of damage to the animal’s nervous tissues, organs or the whole body. Changes in the function, metabolism, morphology and structure of diseases, or various diseases, use this method to study the occurrence and development of human diseases, and provide a theoretical basis for studying the prevention and treatment of human nervous system diseases.
Figure 1. Histological observation of the brains of C57BL/6 mice infected with 106 yeast cells of Pb.
(Patrícia Campi Santos et al. Journal of Neuroparasitology 2010)
Creative Diagnostics has established several different intracranial infection models ranging from bacteria such as Haemophilus influenzae, Streptococcus pneumoniae, and Neisseria meningitides to virus such as enteroviruses, mumps virus and lymphocytic choriomeningitis virus.
Organisms involved in an intracranial infection include the following:
Groups of 8-week-old mice were anesthetized by intramuscular injection of ketamine (0.2 mg/kg) containing acepromazine and atropine. A 10-mm incision was made through the scalp at the midline. A hole was drilled in the skull to the depth of 1.0 mm, 6.0 mm posterior to the orbit and 4.0 mm lateral to the midline, using a sterile pin vise equipped with a sterile high-speed steel drill bit with a diameter of 0.74 mm. Mice were challenged with yeast cells by direct injection into the cranial vault with a 27-gauge needle and Hamilton Gastight syringe. Following inoculation, incisions were sutured with sterile suture material.
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