microbial disorders of the nervous system (wk 6) Flashcards
what is bacterial meningitis
–> which part of the meninges
inflammatory infections of the meninges
(particularly the two internal ones, the pia and arachnoid mater)
what does bacteria in the menginges symptoms
Induces meningial swelling, restricting CSF flow and putting pressure on the organs, causing nausea, pain, vomiting, reduced brain function
if bacteria meningitis is in the spinal cord what can happen
muscles of the neck will become stiff and motor control will be reduced
what happens in encephalitis;; bacterial menignitis that effects the brain
sensory perceptions are decreased, behavioural changes occur, and coma or death may result
what is the test for bacterial meningitis
what is a positive and negative test
lumbar puncutre/ spinal tap
positive test= cloudy CSF
negatie test= clear CSF
which opportunistic members of normal microbiota
Staphylococcus aureus
Steptococcus pyogenes
Klebsiella pneumoniae
what regular disease causing bacteria can cause bacterial memingisti (90%of cases)
Streptococcus pneumoniae
Haemophilus influenzae
Listeria monocytogenes
Neisseria meningitidis
what does neisseria meningitidis cause?
meningococcal meningitis
what are nesirreria meningitidis virulence factors?
fimbriae and polysaccharide capsules, Lipooligosaccharide (with Lipid A/Endotoxin), and various factors to prevent digestion in phagocytes
what mechanism does neisseria meningitidis work through?
blebbing –> it releases endotoxin without dying
what is the leading cause of meningitis
streptococcus pneuomniae
what are streptococcus pneumonia virulence factors?
what is the primary virulent factor?
capsule, secretory IgA protease, pneumolysin (inactivator of lysosomal enzymes)
phosporylcholine (attachment to cells of lungs, meninges, blood vessels – and triggers endocytosis)
in which type of people can listeria monocytogenes cause meningitis in?
Causes meningitis in immunocompromised individuals, but only mild flu in healthy adults.
how can you get listeria monocytogenes
contaminated food/drink
what is listeria monocytogenes
Gram +ve coccobacillus found in soil, water, and many animals (no endospores)
Avoids immune system detection by dividing inside macrophages and epithelial cells
how does listeria monocytogenes work
gets phagocytose and divides and then hijacks actin cytoskeleton to move –> creates a false pseudopod that allows it to go into another cell and infect in by an endosome
Streptococcus pneumoniae
Haemophilus influenzae
Listeria monocytogenes
Neisseria meningitidis
how do you get all these bacteria
and how do they spread
N. meningitidis, H. influenzae, S. pneumoniae – inhaled in respiratory droplets
Listeria – unpasteurized milk, cheese, meat
Bacteria usually spreads to meninges from infections of lungs,
sinuses, or inner ear
Head or neck trauma may expose meninges directly
Bacteria ferment glucose in CSF for energy
how to prevent bacterial meningitis
Susceptible individuals should avoid undercooked veggies, unpasteurized milk, undercooked meat and all soft cheese
People living in dormitories should receive vaccinations
what is the causative agent of Hansens disease (leprosy)
mycobacterium leprae
Signs of disease may not be present for 10-30 years, but when the population becomes big enough, your immune system will aggressively attack them
what is the optimal growth for mycobacterium leprae
Optimal growth – 30°C – so in the chilly parts of your body (peripheral nerve endings, earlobes, nose, tips of fingers and toes.
causative agent of botulism?
clostridium botulinum toxin
NOT AN INFECTION; just the toxin
what are the 2 types of botulism
food borne, infant and wound
Foodborne/Wound Botulism symptoms: paralysis of all voluntary muscles, blurred vision, nausea (death from respiratory paralysis
Infant botulism: not ingested, but C. botulinum can infect GI tract due to absence of microbiota
how does the botulism toxin act at the neuromuscular junction?
botulism blocks the release of acetylcholine at a neuromuscular junction –> no muscle contraction (relaxed)
tetanus causative agent
clostridium tetani
how does clostridium tentani (tetanus enter)
endospore enter through breaks in skin
signs. symptoms of clostridium tentani (tetanus)
tightening of jaw and neck muscles, difficulty swallowing, fever, spasms
treatment or prevention of clostridium tentani (tetanus)
Treatment: aggressive treatment of wound, antibiotics
Prevention: Vaccination
how does the tetanus toxin (tetanospasmin) work
blocks the release of inhibitory neurotransmitter at muscle so that is fully contracted and cant relax
what relaxes muscles vs what contract muscles
tetanus toxin (tetanospasmin) contracts
botulism toxin= relax
West Nile virus transmission cycle
starts with mosquito who usually bites crows and dont make them sick but when birds fly away mosquitos start biting mammals and human
West Nile virus
transmitted by?
incubation period?
symptoms?
Transmitted by mosquito bite
Incubation period of 3-14 days
20-30% get flu-like illness called
West Nile Fever
80% - NO symptoms
what happens when West Nile virus gets into the CNS
neuroinvasion in 1/150 people
Headache
Ocular manifestations
Muscle weakness
Cognitive impairment Polio-like flaccid paralysis
10% mortality
West Nile virus replicative cycle in human
via dendritic cells goes in lymph node which releases TNFalpha making BBB more permeable and causes encephalitis in CNS or via viremia it spreads to spleen via blood stream
who will die from west nile virus
> 70 years old
prevent west nile
mosquito control and repellent
poliomyelitis - poliovirus sym,ptpsm
flaccid paralysis, muscle weakness, atrophy of limbs
how do you get poliovirus
fecal oral root gets in mucus into lymph node and then viremia in extra neural tissue into spinal cord via muscles
and spread systematically via blood
poliovirus in mice
CD155 transgenic mice
polio time course (DIAGRMA)
incubation- 7 days
systemic - 5 days
neural- 5 days (headache, nausea, sore throat)
recovery
how does polio spread? what do humans act as? weather?
Humans are the only known reservoir
Spread by fecal-oral transmission
Peaks during warm months in temperate climates
Complication: post-polio syndrome
30-40 year interval 25-40%
Not an infectious process
why has polio decreased so much
vaccine
polio in 1900s as an epidemic
Polio has only minor symptoms for infants and adults (seems like a mild cold)
Early in the 1900s, white, wealthy children starting getting paralytic polio
Connection to modern plumbing, sewer systems, etc.
1988: 350000 cases; 2000s: ~1000 cases/year
- Americas/Europe: now “polio-free”
