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M & D > Ch 26: Nervous System Infections > Flashcards

Ch 26: Nervous System Infections Flashcards

1
Q

Three layers of membranes of the central nervous system

A

meninges

Dura mater (outermost)

Arachnoid mater

Pia mater (innermost)

Between arachnoid mater and pia mater is the aubarachnoid space filled with cerebrophinal fluid (CSF)

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2
Q

Blood-brain barrier

A

blood vessels are on top of pia mater, capillaries are less permeable, have less pores and tighter junctions than other capillaries

prevents microorganisms entering into the CSF

CSF normally sterile

prevents antibiotics and other drugs from entering the CSF

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3
Q

Bacterial meningitis

A

neisseria meningitdis (gram negative cocci)

Haemophilus influenzae (Gram neg coccobacillus)

Streptococcus pneumoniae (Gram psotive cocci)

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4
Q

Transmission of Bacterial Meningitis

A

airborne

colonization of mucous membranes of the nasopharynx and oropharnynx

cross membrane and enter blood stream

colonize meniges, inflammation

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5
Q

Falality rates of bacterial meningitis

A

up to 70% fatality rate with no treatment

15% with treatment

20% with permanent damage

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6
Q

symptoms of bacterial meningitis

A

fever, severe headache, stiff neckw, nausea, vomiting, confusion, coma, convulsions

Fast onset- Neissseria infections can go from first symptoms to death in less than 12 hours

unique sign = petechial rash (small, flat red pathces of hemorrhaging) due to lipooligosaccharide endotoxin

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7
Q

VIrulence factors of Meningococcal meningitis

A

unique sign = petechial rash (small, flat red pathces of hemorrhaging) due to lipooligosaccharide endotoxin

pili, capsule, IgA protease, invasion factors Opa and Opc

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8
Q

vaccines of menigococcal meningitis

anti-capsule vaccines

A

Quadravalent anit-A, C, W, Y

Anti-B

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9
Q

vaccines of menigococcal meningitis

A

anti-capsule

3rd gen cephalosporisn (+ vanco if resistant = if MRSA), penicillinn G

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10
Q

vaccines of pneumoococcal meningitis

PCV13

A

classic capsule vaccine, contains capsular material from 13 most common 13 pneumoniae strains

=> conjugate

88% drop in invasive Streptococcal disease including meningitis since introduciton fo PCV7

3rd gen cephalosporisn (+ vanco if resistant or meropenem)

vaccines owrk good for viruses, but not so mmuch for bacteria UNLESS they make toxins or capsules

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11
Q

Haemophilus meninitis

A

usually seen in young children

haemophilus influenzae B (Hib) vaccine

incidence has decreased by 94% with the introduction of the HIb vaccine

Ampicillin or 3rd gen cephalosporins (+ vancomycin if resistance or meropenem), doxycyclin, fluroquinolones

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12
Q

Tetanus and tetanus toxin

A

Clostridium tetani

Gram-positive, anaerobic sporulating bacteria => spore forming disease when dirt gets in a cut

disease due to toxin production => tetanus neurotoxin (TeNT)

LD50 of toxin is approx 2.5-3ng/kg

incbation perioud is usually about 1 week, incubation period is longer the further the injury site is form the central nervous system

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13
Q

Localized tetanus

A

affects local muscles, spasms, no CNS involvement

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14
Q

Generalized tetanus

A

Retrograde transport of TeNT up peripheral neurons to CNS

TeNT is an AB toxin which inhibits the release of neurotransmitters

Muscle spasm of jae (lockjaw) followed other muschles, arching of back, rupture of tendons and breaking of bones

spasms in larynx and diaphragm leading t asphyxiation

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15
Q

Treatment of generalized tetanus

A

wound debridement, use of ventilator, TeNT antiserum, benzodiazepines (Tranquilizers)

antibiotics include penicillin or metronidazole

tetanus toxoid vaccination

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16
Q

Types of Rabies

A

Viral disease transmitted by bite through saliva

Family Rhabdoviridae, Genus Lyssavirus

7 or 8 species or genotypes

rabies virus 1
lagos bat virus 2
Mokola virus 3
duvenhage virus 4
european bat virus type 1 and type 2 [5,6]
australian bat virus
17
Q

Rhabdoviridae genome

A

ssRNA non-segmented (-) sense genome 12 kb

5 genes

N nucleoprotein
P phosphoprotein 
M matrix protein
G glycoprotein
L RNA-dependent RNA polymerase
18
Q

Physiology of the Rhadoviridae

A

bullet shaped virion

inside is teh ribonucleoprotein (RNP) , a helical RNA molecule associated with the N, P and L proteins
=>nuclear protein associated with the nuclear portion of the genome, phosphoprotien binds the RNA, and L is the DNA polymerase

surrounded by an outer envelope composed of Ma nd G glycoprotiens and host-derived lipoproteins

19
Q

Rabies transmission

A

reservoir is bats and various animals

raccoons, skunks, foxees, dogs, coyotes

humanss are dead end hosts

transmission by bite of infected animal

virus is found in the saliva

minor aerosol transmission route - bate caves, labs

orga/ tissue transplantation

20
Q

Rabies incubation

A

incubation period of 20-90 days but up to a year

probability of infection and time on incubation depend on anatomical location of the bite

closer to the head more likely infection and shorter time of incubation

21
Q

two forms of rabies

A

paralytic 20%

encephalytic 80%

22
Q

Paralytic rabies

A

flaccid paralysis

weakness in bitten extremity, spreading outwards

23
Q

encephalytic rabies

A

furious rabies

periods of hyperexcitability separated by lucid periods

confusion, hallucinations, agitation, aggressive behaviour

fever

hypersalivation, sweating, crying, dialated pupils

hydrophobia

pain on swallowwing, contractions of diaphragm and throat

24
Q

pathology of rabies

A

bite introduces virus into tissue

local replication of the virus in muscle fibres

virus infects peripheral nerves then spreads towards teh CNS then towards the brain

infects many but not all brain cell types

spread from brain to salivary glands through nerves

relatively minor CNS tissue destruction

may be changes in neurotransmitters, ion channels, cellular protiein synthesis

25
Q

Rabies epidemiology

A

estimates of 55000 deaths per year world-wide

mostly in nepal, rural india, china, africa and sounth and central america

99% of fatalities in developing countries

most cases are a result of dog bites

26
Q

rabies vaccine

A

vaccination as prophylaxis after you are biten

vaccinaiton of dogs

vacciation of wildlife or animals

vacciation in a circle around a biten infection

neutralization of virus in extremities after expousure but before dissemination into the CNS

M & D (18 decks)

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