1. Microbiology: A Systems Approach
PowerPoint to accompany
Microbiology: A Systems Approach
Cowan/Talaro
Chapter 19
Infectious Diseases Affecting the Nervous System
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2. Chapter 19
Topics
- Nervous System Defenses
- Nervous System Diseases

3. Nervous System Defenses
Normal flora

4. Nervous system
Central nervous system (CNS)
Peripheral nerves

5. CNS
Brain
Spinal cord
Neurons – cells that make-up the brain and spinal cord
Defenses

6. Defenses Meninges – surround the brain and spinal cord
Cerebrospinal fluid (CSF)
Bone casing
Blood-brain barrier
Immunologically privileged

7. A diagram of the central nervous system and the peripheral nerves.
Fig Nervous system.

8. Important structures of the brain and spinal cord that are associated with defenses.
Fig Detailed anatomy of the brain an spinal cord.

9. Normal flora
Absent
Viruses can exist in a dormant state in the nervous system

10. Nervous System Diseases
Meningitis
Neonatal meningitis
Meningoencephalitis
Acute encephalitis
Subacute encephalitis
Rabies
Poliomyelitis
Tetanus
Botulism
African sleeping sickness

11. Meningitis Many different species of bacteria
Neisseria meningitis
Streptococcus pneumoniae
Haemophilus influenzae
Listeria cytogenes
Coccidiodes immitis
Yeast – Cryptococcus neoformans
Co- or previous viral infections can facilitate meningitis

12. A transmission electron micrograph (TEM) of Neisseria, a causative agent of meningitis.
Fig Transmission electron micrograph of Neisseria.

13. Serious complications of meningococcal infections are meningococcemia, where the bacterium can enter the blood and escape into the CSF.
Fig Dissemination of the meningococcus
from a nasopharyngeal infection

14. An oxidase test can help determine the presence of Neisseria or Branhamella, which are bacteria that can cause meningitis.
Fig The oxidase test.

15. Gram stains can be used to identify the unique palisades (cellular arrangements) for Listeria monogenes, a bacterium that can cause meningitis.
Fig Listeria monocytogenes

16. Encapsulation and budding are unique morphological characteristics that can be used to identify the yeast Cyptococcus neoformans, a causative agent of meningitis.
Fig Crytococcus neoformans from infected spinal
Fluid stained negatively with India ink.

17. The binding of yeast to the meninges or brain can produce a gelatinous exudate.
Fig Cyptococcosis

18. The stages in coccidiodes infection, and the development of coccidiodomycosis.
Fig Events in coccidiodes infection and
Coccidiodomycosis.

19. Areas in the United States that are endemic for Coccidoides immitis, the causative agent of meningitis.
Fig Areas in the U.S. endemic for Coccidoides
Immitis.

20. Features of meningitis caused by different species of bacteria, and viruses.
Checkpoint 19.1 Meningitis

21. Neonatal meningitis Bacterial infection
Contracted from mother (utero or birth canal)
Premature babies (immature immune system) are at risk

22. Features of neonatal meningitis.
Checkpoint 19.2 Neonatal meningitis

23. Meningoencephalitis Protozoa infection
Naegleria fowleri
Acanthamoeba
Inflammation of the brain (encephalitis)
Accidental infection

24. Scanning electron micrograph of Naegleria fowleri, the causative agent of amoebic meningoencephalitis.
Fig Scanning electron micrograph of Naegleria
Fowleri.

25. Features of meningoencephalitis.
Checkpoint 19.3 Meningoencephalitis.

26. Acute encephalitis Viral infection Arboviruses Herpes simplex 1 or 2
JC virus

27. Arboviral encephalitides is prevalent worldwide.
Fig Worldwide distribution of major arboviral
Encephalitides.

28. Features of acute viral encephalitis.
Checkpoint 19.4 Encephalitis

29. Subacute encephalitis
Mostly a protozoan infection
Viral infection
Prion infection
Symptoms develop slowly

30. The life cycle and morphological forms of the protozoan Toxoplasma gondii, the causative agent of subacute encephalitis.
Fig The life cycle and morphological forms of
Toxoplasma gondii.

31. Comparison between a normal and prion infected brain tissue sample.
Fig The microscopic effects of spongiform
Encephalopathy.

32. Features of subacute encephalitis caused by protozoan, viral, and prion agents.
Checkpoint 19.5 Subacute encephalitis

33. Rabies Viral infection Slow, progressive zoonotic disease Fatal
Distinct pathogenesis and symptoms

34. The rabies virus has a unique bullet-like structure.
Fig The structure of the rabies virus.

35. Observing neuronal brain cells with intracytoplasmic inclusions (Negri bodies) is a method of diagnosing rabies.
Fig Diagnosis of rabies.

36. Features of rabies.
Checkpoint 19.6 Rabies.

37. Poliomyelitis Viral infection Spinal cord infection Common vaccine
Small children are at risk
Neurotrophic
Paralytic

38. The anterior horn of the spinal cord is a target for the poliovirus.
Fig Targets of poliovirus.

39. The poliovirus has a unique icosahedral capsid shell.
Fig Typical structure of a picornavirus.

40. The unique stages of infection and pathogenesis of poliomyelitis.
Fig The stages of infection and pathogenesis
of poliomyelitis.

41. The level of severity of a poliovirus infection can vary.
Fig Diagrammatic representation of possible
outcomes of poliovirus infection.

42. Features of poliomyelitis.
Checkpoint 19.7 Poliomyelitis

43. Tetanus Bacterial infection Neuromuscular disease
Tetanospasmin (neurotoxin)
Endosporulation and germination

44. Clostridium tetani, the causative agent of tetanus, have a unique tennis racket morphology.
Fig C. tetani

45. Neonatal tetanus can occur due to application of mud, dung, or ashes to the umbilical stump.
Fig Neonatal tetanus

46. Bacterial invasion, release of bacterial toxin, and symptoms associated with tetanus.
Fig The events in tetanus.

47. Features of tetanus.
Checkpoint 19.8 Tetanus

48. Botulism Bacterial infection Exotoxin Forms
Food-borne
Infant
Wound
Infectious – botulin toxemia
Can cause fatalities in livestock

49. Botulin can prevent the release of acetylcholine, thereby muscle contractions do not occur.
Fig The physiological effects of botulism toxin.

50. Features of botulism.
Checkpoint 19.9 Botulism

51. African Sleeping Sickness
Protozoan infection
trypanosomiasis
Infects humans, domestic animals and wild mammals
Prevalent in African

52. The life cycle and spread of Trypanosoma brucei, the causative agent of African sleeping sickness.
Fig The generalized cycle between humans and the
Tsetse fly vector.

53. Features of African sleeping sickness.
Checkpoint African sleeping sickness.

54. Summary of the diseases in the nervous system.
Taxonomic organization of microorganisms causing

55. Infectious Diseases Affecting the Nervous System.
Fig. 19.p608