Slide 1
Microbial Diseases: Nervous
System
Lecture 26
Slide 2
Biol 240 S06 2
Learning Outcomes
•Nervous System
•Meningitis
•Encephalitis
• Exotoxins of
Clostridium sp
•Leprosy
•Rabies
•Polio
•Arboviruses
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Microbial Diseases of the Nervous System: Understanding Meningitis and Encephalitis - Prof, Study notes of Microbiology
An in-depth look into microbial diseases that affect the nervous system, focusing on meningitis and encephalitis. Learn about the causes, symptoms, diagnosis, and treatments for these conditions, as well as the role of the blood-brain barrier and meninges in protecting the brain.
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Slide 1
Microbial Diseases: Nervous
System
Lecture 26
Slide 2
Biol 240 S
Learning Outcomes^ • Nervous System• Meningitis• Encephalitis• Exotoxins of
Clostridium sp
- Leprosy• Rabies• Polio• Arboviruses
Slide 3
Biol 240 S
3
Nervous System
- Entry of Microbes to
CNS:-– Skull or backbone
fractures
- Medical procedures– Along peripheral
nerves
-^
via blood or lymph
Slide 4
Biol 240 S
Microbial Diseases of the Nervous
System
- Microbes can grow in the
cerebrospinal fluid in thesubarachnoid space of the CNS
- The blood brain barrier (capillaries)
prevents passage of some materials(such as antimicrobial drugs) into theCNS
- Meningitis
- Inflammation of meninges
- Encephalitis
- Inflammation of the brain
- Encephalitis
- Inflammation of meninges
What is the blood-brain barrier? Describe its’ role inprotecting the brain, and the problems this cause intreating bacterial forms of meningitis.Explain the difference between meningitis and encephalitis.
Slide 7
Biol 240 S
7
Bacterial Meningitis
Table 22.
One of the fist clinical tests done on a suspected case ofbacterial meningitis is a gram stain. Where would youobtain a sample, and how could you use a gram stain todistinguish between the 3 major causes of bacterialmeningitis.
Slide 8
Biol 240 S
- Occurs mostly in children (6 months
to 4 years)
- Gram-negative aerobic rod, normal
throat microbiota– Capsule antigen type b
- Prevented by Hib (conjugate) vaccine
Haemophilus influenzae
Meningitis
Slide 9
Biol 240 S
9
Haemophilus influenzae
Meningitis
Figure 22.
Why are infants and newborns more susceptible tobacterial meningitis?
Slide 10
Biol 240 S
Meningococcal Meningitis
Neisseria meningitis
-^
Aerobic, Gram -,encapsulated cocci
-^
Present in 10% ofnoses
-^
Symptoms caused byendotoxin
-^
Rash–
Does not fade whenpressed
-^
Students
-^
Untreated mortalityrate 85%
Why are students and military recruits more likely tocontract bacterial meningitis than ranchers? Select one organism that causes meningitis and explainhow it enters the body and then how it enters the CNS.
Slide 13
Biol 240 S
13
Tetanus
Clostridium tetani
-^
Gram-positive,endospore-forming,obligate anaerobe
-^
Grows in deep wounds–
Anaerobic conditions
-^
Exotoxin Tetanospasmin
-^
A-B toxin
-^
binds to nerve cells
-^
vaccination with tetanustoxoid (DTP) andbooster (dT)
-^
Treatment with tetanusimmune globulin
Explain the differences between the paralysis cause byClostridium tetani and .C. botulinum, what is responsiblefor the paralysis.What are the preventative and post exposure treatmentsfor tetanus and botulism?
Slide 14
Biol 240 S
Clostridium botulinum
- Gram-positive, endospore-forming, obligate
anaerobe
- Intoxication due to ingesting botulinal toxin• Botulinal toxin blocks release of acetylcholine
neurotransmitter causing flaccid paralysis
- Prevention:
- Proper canning– Nitrites prevent endospore germination in sausages
Botulism
Explain the differences between the paralysis cause byClostridium tetani and .C. botulinum, what is responsiblefor the paralysis.What are the preventative and post exposure treatmentsfor tetanus and botulism?
Slide 15
Biol 240 S
15
Mycobacterium leprae
- Acid-fast rod that
grows best at 30°C
- Grows in peripheral
nerves and skin cells
- Transmission requires
prolonged contact withan infected person
Leprosy
Which organism causes Hansen’s disease?Describe the transmission of leprosy, and describe how thedisease progresses in each of the two different forms of thedisease.
Slide 16
Biol 240 S
Leprosy
- Tuberculoid (neural)
form: Loss of sensationin skin areas; positivelepromin test
- Lepromatous
(progressive) form:Disfiguring nodules overbody; negative lepromintest
Which organism causes Hansen’s disease?Describe the transmission of leprosy, and describe how thedisease progresses in each of the two different forms of thedisease. 2 main forms
Slide 19
Biol 240 S
19
Eradication of Polio
-^
Endemic Polio 4 countries2004)–
Nigeria, India, Afghanistan,Pakistan
-^
(11 in 2007)
-^
DRC, Sudan, Niger, Chad,Myanmar
-^
Epidemics
-^
Introduced from endemiccountries by travelers
-^
Education
-^
Cultural Barriers
Provide two possible problems facing the World HealthOrganization in its quest to eradicate Polio worldwide?
Slide 20
Biol 240 S
Rabies
- Transmitted by
animal bite
- Virus multiplies in
skeletal muscles,then brain cellscausing encephalitis
- Initial symptoms
may include musclespasms of the mouthand pharynx andhydrophobia
Describe the transmission of the rabies virus and theprogression of the disease.
Slide 21
Biol 240 S
21
Rabies
- Furious rabies• Paralytic rabies• Preexposure
prophylaxis:
- Postexposure
treatment:– Vaccine + immune
globulin
Describe the transmission of the rabies virus and theprogression of the disease.
Slide 22
Biol 240 S
Rabies virus (Rhabdovirus)
Figure 22.
Slide 25
Biol 240 S
25
Primary Amoebic
Meningoencephalitis
-^
Naegleria fowleri
-^
fresh water Protozoan–
ponds
-^
Flagellated forminfects nasal mucosa
-^
Penetrates to thebrain
-^
Feeds on host tissue
-^
100% fatal
-^
rare
Describe how someone might contract Primary AmebicMeningoencephalitis.
Slide 26
Biol 240 S
Transmissible Spongiform
Encephalopathies
-^
Caused by prions–
Sheep scrapie
-^
Creutzfeldt-Jakobdisease
-^
Kuru
-^
Bovine spongiformencephalopathy
-^
Transmitted byingestion or transplantor inherited
-^
Chronic, fatal
What are prions, how do they reproduce, and describe theepidemiology of a prion disease of your choice.