Chapter 22 - Microbial Diseases of the Nervous System Flashcards by Maeryn O

What are meninges?

-3 continuous membranes: dura mater, arachnoid mater, pia mater

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Subarachnoid Space

-between pia mater and arachnoid mater
-houses CSF

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Blood Brain Barrier

-capillary system that prevents the passage of some substances but not others

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Drugs cannot cross the BBB unless they are ____ soluable

lipid

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What is a common lipid-soluable antibiotic?

chloramphenicol and sometimes penicillin in large amounds

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Meningitis

inflammation of the meninges

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Encephalitis

inflammation of the brain

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Meningoencephalitis

when both the brain and meninges are inflamed

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Initial Meningitis Symptoms

-fever
-headache
-stiff neck

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Secondary Meningitis Symptoms

-nausea
-vomiting

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Possible Progressions of Meningitis

-convulsions
-coma
-death

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The progression of meningitis may only take ___ hours.

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Kernig’s Sign

-a diagnostic tool in older or younger patients
-non-invasive
-stiffness when they bend their hamstrings

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How is meningitis diagnosed?

spinal tap

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What is a spinal tap?

-collection of a CSF sample from the spinal cord
-needle inserted between L3 and L4

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Serology of Meningitis

-use a gram stain to diagnose
-keep the sample culture at storage temp and move quickly

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What is used to treat bacterial meningitis?

3rd generation cephalosporins

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*What is not reccomended to treat bacterial meningitis?

chloramphenicol due to adverse effects?

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Haemophilus Influenzae

-aerobic
-gram-negative
-has a capsule
-member of normal throat microbiota
-can cause meningitis when it enters the bloodstream

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How many strains of H. influenzae are there? Which most commonly causes disease? Why?

-6 strains classified by capsular antigens
-strain B causes 95% of cases

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Hib Meningits occurs mostly in _______

children under age 4

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Is there a vaccine for H. influenzae meningitis

Yes: HiB vaccine
-it can be effective by 6 months of age
-is given at 6 weeks of age

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Meningococcal Meningitis is cause by which bacteria?

Neisseria meningitidis

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N. Meningitidis

-aerobic
-gram-negative
-diplococcus
-has a capsule
-present in the nose and throat of carriers

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How is N. meningitidis spread?

-droplet or contact

What are the strains of N. meningitidis? Which is the most common?

-strains A, B, C, W135, X, Y -C is the most common

Who are commonly affected by N. meningitidis?

-children under 2 -college students

How long is the progression of N. meningitidis?

-it is fast -may only be 24 hours

What are the primary symptoms of N. meningitidis?

throat infection that spreads to the blood stream

What are the secondary symptoms of N. meningitidis?

throbbing headache

Is there a vaccine for N. meningitidis?

yes

What are possible effects of N. meningitidis?

-necrosis that may lead to amputation -deafness -paralysis -death

Petichiae

-rash associated with necrosis

Where does Streptococcus pneumoniae commonly reside?

-nasopharyngeal region

What % of the population are carriers of S. pneumoniae?

70%

Streptococcus pneumoniae

-gram-positive -capsule -diplococci

What is the leading cause of bacterial meningitis?

S. pneumoniae

Who is commonly affected by S. pneumoniae meningitis?

children between 1 month and 4 years

What is the mortality rate of S. pneumoniae meningitis in children?

What is the mortality rate of S. pneumoniae meningitis in elderly?

22%

How many strains of S. pneumoniae are there?

90-92 strains

Is there a vaccine for S. pneumoniae?

-yes; the most common 20 strains have a vaccine

How does S. pneumoniae enter the blood stream?

-pneumonia -otitis media -surgery/trauma to the head or neck region

What is usually used to treat S. pneumoniae?

penicillin

Listeria monocytogenes

-gram-positive -rod

How is L. monocytogenes spread?

-food, soil, water -it is a psychotroph

When is L. monocytogenes dangerous?

during pregnancy (still born) or in immunocompromised people

Listeriosis is the _____ most common cause of bacterial meningitis.

fourth

What is the infant mortality rate of L. monocytogenes?

60%

What antibiotic is used for Listeriosis?

Penicillin G

When can E. coli cause meningitis?

in newborns

The bacteria that cause meningitis are usually carried by ________.

healthy people

What is used in prevention of meningitis?

-vaccine -hygiene - not sharing drinks, lip balm, food utensils, etc.

Clostridium tetani

-obligate anaerobe -endospores -gram-positive -rod

Where is C. tetani common?

soil contaminated with animal feces

What causes the symptoms of tetanus?

-A-B exotoxin: tetanospasmin

How does tetanospasmin act?

-it is released upon lysis of bacteria -enters CNS via PNS or blood -no inflammation

What does tetanospasmin block at the neuromuscular junction?

the relaxation pathway

What neurotransmitter does tetanospasmin inhibit?

GABA

What are the symptoms of Tetanus?

-muscle spasms -lock jaw -stiff neck -opisthotonos: bent spine

How does Tetanus cause death?

-spasms of the muscles in the cardiovascular and respiratory system

What is needed for Tetanus to take action?

-anaerobic growth conditions ie. improperly cleaned deep wound caused by rusty nails

Is there a vaccine for Tetanus?

yes: DTaP

What type of vaccine is DTaP?

-toxoid - inactivated toxin

What bacteria causes Botulism?

Clostridium botulinum

-obligate anaerobe -endospores -gram-positive -rod

Where is C. botulism found?

soil and many aquatic sediments

What does the botulinal A-B exotoxin do?

-blocks ACh at the neuromuscular junction

What does C. botulinum do?

-causes lost muscle tone and leads to flacid paralysis

Symptoms of Botulism

-abdominal distress -nausea -diarrhea or constipation -blurred/double vision with dilated pupils

How long does C. botulinum take to show its full effect?

12-36 hours

What are the strains of C. botulinum? Which affect humans?

-strains A, B, C, D, E, F, G -humans affected by A, B, E, F

Where do humans usually contract C. botulinum?

-canned foods (except for tomatoes) -processed foods

Which bacteria causes Leprosy?

Mycobacterium leprae

What is another name for Leprosy?

Hansen's Disease

M. leprae

-rods -acid-fast -grow optimally at 30℃

How does M. leprae act?

by invading the PNS

How is M. leprae transmitted?

by prolonged contact with an infected person

Paucibacillary/Tuberculoid/Neural Form of Leprosy

-entered by cell mediated immunity

What characterizes the paucibacillar form of leprosy?

-discoloured skin regions that have lost sensation -surrounded by a border of nodules

Which leprosy is faster to recover from?

Paucibacillary (6 months) vs multibacillar (24 months)

Multibacillary/progressive Leprosy

-cell mediated immunity has failed -progressive form

Multibacilliary Leprosy symptoms?

-disfuguring nodules all over the body -mucous membrane of the nose infected -lion face -claw shaped hand -loss of fingers and toes

What is the diagnostic test for leprosy?

acid-fast stain or blood test

How is leprosy treated?

-dapsone (sulfa drug) -rifampin -clofazimine -usually all combined

What is clofazimine used for?

to minimize antibiotic resistance

What causes Polio(myelitis)?

poliovirus

How is polio transmitted?

by ingestion (fecal/oral contamination)

What are the initial symptoms of polio?

-headache -sore throat -fever -nausea

Polio: People with good immunity

-transient infection -show no symptoms

How many people are affected with the paralytic form of polio?

less than 1%

Polio: People with bad immunity

-when good immunity fails -persistent viremia (enters blood) -virus enters motor neurons -grows in cell bodies to kill neurons -leads to paralysis

How can polio cause death?

paralysis of respiratory muscles

Is there a polio vaccine?

yes, two actually

Salk Vaccine

-1955 -inactivated form of all 3 viruses -IPV inactivated polio vaccine -needs boosters -has to be injected

Sabin Vaccine

-1963 -weakened version of the virus -OPV oral polio vaccine -less expensive -no need for boosters -1 in a million revert back and cause the actual disease