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Nervous System Infections

Explore central and peripheral nervous system infections, including meningitis and tetanus, their signs, prevention, and treatments. Learn about bacterial causes, symptoms, epidemiology, and vaccination strategies.

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Nervous System Infections

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  1. Nervous System Infections Chapter 20

  2. Nervous system • Central nervous system (CNS) • Brain • Encephalitis • Spinal cord • Peripheral nervous system (PNS) • Bundles of thin extensions from nerve cells called axons

  3. Two basic cell types • Neuroglia • Provide support • Neurons • Carry nerve impulses • Nucleus in the cell body • ganglion

  4. Defenses • Meninges • Meningitis • Cerebrospinal fluid (CSF) • Bone casing • Blood-brain barrier

  5. Structures of brain and spinal cord

  6. Normal flora • None • Viruses can exist in a dormant state in the nervous system • penetrate CNS by traveling up nerve bundles • Herpes simplex and rabies viruses

  7. Bacterial Meningitis • Pathogens and virulence factors • Streptococcus pneumoniae – leading cause in adults • Neisseria meningitidis – epidemic, fimbriae, capsule, and endotoxin • Haemophilus influenzae – leading cause prior to vaccine • Listeria monocytogenes –listeriosis infetuses, pregnant women, and immunocompromised individuals • Streptococcus agalactiae – causes most cases of newborn meningitis

  8. Neisseria Streptococcus

  9. Haemophilus Listeria

  10. Signs and symptoms • Acute high fever and severe meningeal inflammation • Inflamed cranial meninges – severe headache, vomiting, pain • Inflamed spinal meninges – stiff neck, altered muscle control • Encephalitis may cause behavioral changes, coma, and death • Petechiae may appear on skin

  11. Epidemiology • S. agalactiae acquired during birth • Listeria transmitted via contaminated food • S. pneumoniae, Neisseria & Haemophilusall transmitted via respiratory droplets • S. pneumoniae present in throat of 75% of humans without causing harm • Meningococcal meningitis is the only form that becomes epidemic

  12. Diagnosis • Based on symptoms and culturing of bacteria in CSF from spinal tap

  13. Prevention • Vaccines available for S. pneumoniae, H. influenzae, and N. meningitidis • Individuals at risk for listeriosis should avoid high-risk foods (milk, cheeses, undercooked meat) • Mass prophylaxis with ceftriaxone or rifampin helps control epidemics of meningococcal form • Treatment • ceftriaxone or penicillin

  14. Tetanus • “Lockjaw” • Causative agent • Clostridium tetani • Anaerobic • Gram positive • Bacillus • Spore former

  15. Signs & Symptoms • Tightening of jaw and neck muscles • difficulty swallowing • Restlessness and irritability • Increased contractions spreading to other muscles • Back spasms • Difficulty breathing and death • Prolonged contraction of diaphragm

  16. Bacteria contained to anaerobic tissue around wound • Tetanospasmin toxin moves to CNS and blocks inhibition of motor neurons causing paralysis • 50-90% mortality rate in untreated cases

  17. Epidemiology • C. tetani found in dirt and dust and GI tract of humans and other animals • Nearly half of infections result from puncture wounds including • Body piercing, tattooing, animal bites, IV drugs • Frequently fatal but rare in the developed world • 30 to 60 cases reported in US annually

  18. Prevention • Immunization with toxiod vaccine • DTaP • Treatment • Thoroughly clean wound • Remove all dead tissue and foreign material • Penicillin to kill multiplying bacteria • Will not destroy endospores • Antitoxin • Neutralizes only circulating toxin

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