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USC Microbiology 1 > Week 11 Diseases of nervous system > Flashcards

Week 11 Diseases of nervous system Flashcards

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Biology 101 flashcards
1
Q

Meninges

A

Three layers: dura mater (in contact with skull), arachnoid mater, pia mater (in contact with blood vessel and brain)
Surrounds brain

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2
Q

Nervous system divisions

A

CNS: brain and spinal cord
PNS: nerves (communication between brain and rest of body)

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3
Q

Bacterial meningitis causes (3) and characteristics

A

Streptococcus pneumoniae, haemophilus influenza, neisseria meningitidis
All have capsule (protection from phagocytosis)
Enter CSF, then die rapidly

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4
Q

Bacterial meningitis symptoms (5)

A

Fever, headache, stiff neck, nausea, vomiting

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5
Q

Other causes of bacterial meningitis (3)

A

Listeria monocytogenes
Streptococci group B
Staphylococci

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6
Q

Haemophilus influenza characteristics

A

Aerobic, gram negative, normal throat flora

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7
Q

H. influenza diseases

A

bacterial meningitis, epiglottitis, otitis media, pneumonia

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8
Q

WHat about h. influenza contributes to pathogenicity

A

Capsular carbohydrate antigen type B (Hib)
Vaccine is based on this antigen

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9
Q

Neisseriaceae characteristics

A

Non spore forming diplococci, aerobic or facultative, gram negative

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10
Q

Pathogenic species of neisseriaceae and location

A

N. gonorrhoea and N. meningitidis
Found on human mucosal membrane

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11
Q

N. meningitidis medium

A

Chocolate agar (brown)- contains red blood cells which are heated and killed

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12
Q

N. meningitidis disease

A

meningococcal meningitidis

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13
Q

N. meningitidis serotypes

A

A (widespread epidemic, africa)
C (North america and other parts of world)
VAccine based on capsular polysaccharide for serotypes A and C
No vaccine for B

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14
Q

N. meningitidis treatment

A

doxycycline, ofloxacin, erythromycin

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15
Q

Meningitis signs and symptoms

A

Appearance of neutrophils and N. meningitidis in CSF smear
Can proliferate in blood leading to sepsis, then enters into nervous system (meninges)
Spreading rash on trunk, arms and legs, form crusty vesicles on skin surface

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16
Q

S. pneumoniae disease

A

streptococcal meningitis

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17
Q

S. pneumoniae location , vaccine, treatment

A

Nasopharyngeal region, vaccine against capsular antigen, penicillin

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18
Q

Clostridium characteristics

A

Obligate anaerobe (lacks cytochromes needed to use O2 as terminal hydrogen acceptor)
Catalase and peroxidase negative
Gram positive
Spore forming (when nutrients insufficient)
Ferments carbohydrates
Encapsulated alpha and theta/gamma? haemolysis

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19
Q

Clostridium species (4) and diseases

A

Perfringens: gas gangrene and food poisoning
Difficile: toxic enterocolitis (antibiotic associated pseudomembrane colitis)
Tetani (spores): tetanus
Botulinum: botulism

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20
Q

C. tetani

A

Obligate anaerobe, common in soil, produces spores
Potent neurotoxin (tetanospasmin) released when lysed or killed
Non communicable as does not spread from infectious site

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21
Q

Tetanospasmin MOA

A

Blocks relaxation pathways in muscles: they contract but cannot relax leading to paralysis and pain

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22
Q

C. botulinum

A

Spore forming, anaerobe
Produces potent exotoxin under anaerobic conditions
Serological types A-E (5)
Infant botulism can occur due to competition with normal flora

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23
Q

Botulinum exotoxin characteristics

A

Toxin not formed in acidic food eg tomatoes
Toxin destroyed with cooking heat
Type A spore most resistant to heat
Antibiotics not effective against toxin, instead neutralised with antitoxins A-E from mice

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24
Q

Leprosy cause

A

Mycobacterium leprae

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25
Q

Mycobacterium leprae characteristics

A

Acid fast, related to M. tuberculosis
Optimal growth temperature 30 degrees
Long generation time
Cannot be cultured outside body (armadillos used as lower body temp than humans)
Grows in PNS and on skin

26
Q

Forms of leprosy (2)

A

Tuberculoid (neural): regions of skin lose sensation, surrounded by borders of nodules
Lepromatous (progressive): skin cells infected, disfiguring nodules form all over body

27
Q

Tuberculoid leprosy- who it occurs in, diagnosis

A

In ppl with good immune system
Detection of acid fast bacteria in fluid from slit cut in cool site eg earlobe
Lepromin test: extract from advanced form injected into skin yields visible reactive, this test is negative in later stages of the disease

28
Q

Lepromatous leprosy characteristics (5)

A

Occurs in people without effective cell mediated immunity
Mucous membrane of nose and face most affected
Clawed hands
Not very contagious, requires prolonged intimate contact
COmplications may occur but usually does not cause death

29
Q

Viral diseases of nervous system (3)

A

Poliomyelitis
Rabies
Arbovirus encephalitis (eastern equine, western equine, st louise, california, japanese B, yellow fever, Powassan virus, dengue fever, colorado tick borne encephalitis)

Usually result in death

30
Q

Poliomyelitis progression

A

Infection initiated by ingestion of virus
Multiplies in throat and small intestine, invades tonsils and lymph nodes in neck and ileum
Enters blood (viraemia), then central nervous system
Multiplies in cytoplasm of motor nerves and kills them resulting in paralysis

31
Q

Polio diagnosis and prevention

A

Isolation of virus from faeces and throat, cell culture
Vaccines: salk (inactivated with formaldehyde), sabine (live attenuated)
Iron lungs mechanically respirate paralysed lungs

32
Q

Rabies

A

Caused by rabies virus (rhabdovirus, bullet shape)
Always results in fatal encephalitis if untreated by vaccination
Human acquires from infected animal
Long incubation period enough to allow immunity to develop from post exposure vaccination

33
Q

Rabies progression

A

Virus within peripheral nerves not accessible to immune system until cells of CNS destroyed
Agitation period: breakdown of NS cells
Calm period: virus multiplying within NS

34
Q

Rabies symptoms

A

Spasms of mouth muscles and pharynx, hydrophobia, total destruction of CNS cells and death

35
Q

Furious rabies

A

Animal restless, highly excitable, snap at anything within reach eg dog

36
Q

Paralytic rabies

A

Animal not excited, relatively quiet, might snap if irritated eg cat

37
Q

Rabies diagnosis

A

Presence of viral antigen in saliva, serum or CSF using immunofluorescence technique

38
Q

Rabies treatment

A

Anti-rabies vaccine and immunoglobulins post exposure (prophylaxis)
Treatment for any unprovoked bite from animal not available for examination

39
Q

Rabies vaccination (3)

A

Old (pasteur): attenuated, dried spinal cord of rabies infected rabbit
Human diploid cell vaccine (5-6 injections over 28 days)
Passive immunisation: human immunoglobulin

40
Q

Arbovirus disease

A

Arboviral encephalitis

41
Q

Arbovirus naming

A

Initial location of isolation and diseases they produce
Categorised based on morphology, biochemistry and antigenic similarities

42
Q

Rabies carriers

A

Skunk, fox, bat, bobcat, raccoon, dog, cat

43
Q

Arbovirus general characteristics

A

Enveloped virions with single stranded RNA
Envelope contains haemagglutinin and lipoproteins (so can be inactivated by lipid solvents)
Found in blood and tissues, but not stool
Diagnosed using serological techniques

44
Q

What differentiates reoviridiae from other arboviruses

A

Reoviridiae are double stranded RNA viruses without envelopes

45
Q

Reservoir and transmission of arboviruses

A

Infection transmitted from arthropods to susceptible vertebrate host

46
Q

Invertebrate vectors of arboviruses (5)

A

Aedes mosquito, wood tick, tick , anopheles mosquito, flea

47
Q

Survival of arbovirus between seasons (2)- needed as arthropods are not present in all seasons

A

Infected adult arthropods hibernate between seasons to survive
Transovarian transmission: infected female arthropod transmits virus to progeny

48
Q

Mechanism of arboviruses

A
  1. Infection of vertebrate by a biting arthropod
  2. Virus amplifies in reticuloendothelial system
  3. Virus become localised in various target organs causing
    cell necrosis, and inflammation which leads to fever
  4. Transmission along neural pathway
  5. Enters CNS causing meningeal inflammation of neuronal dysfunction encephalitis
49
Q

Yellow fever progression

A

Liver and hepatic cell necrosis
Haemorrhage due to failure of liver to produce clotting factor

50
Q

Dengue haemorrhagic fever

A

Fever associated with rash and flu symptoms
Changes in small dermal blood vessels: increased vascular permeability and infiltration of mononuclear cells

51
Q

Arbovirus treatment

A

None other than supportive care

52
Q

Arbovirus prevention

A

Avoiding contact with infected arthropods, elimination of arthropod bleeding sites, use of insecticides

53
Q

Arbovirus vaccination

A

Immunisation of horses and humans against west and east equine encephalitis

54
Q

Cryptococcus neoformans characteristics

A

Fungal meningitis
Yeast like with spherical cell
Polysaccharide capsule
Mainly in soil contaminated with pigeon droppings

55
Q

Cryptococcus neoformans transmission

A

Inhalation -> lung infection -> blood -> meninges

56
Q

Cryptococcus neoformans identification

A

serology detecting antigen in CSF and blood

57
Q

Trypanosoma gambiense and T rhodesiense

A

Cause african trypanosomiasis (sleeping sickness)
Protozoan parasites
Trypanosoma multiplies in Tsetse fly saliva, transmitted to human through bite
Bite -> blood stream -> spleen lymph nodes and liver

58
Q

Trypanosoma symptoms

A

Invasion of CNS results in reduced concentration, ability to talk and walk
Extreme tiredness -> continual sleeping -> coma -> death

59
Q

Trypanosoma reservoir

A

Game animals, cattle and sheep, common in Africa

60
Q

Bovine spongiform encephalopathy (BSE)

A

Caused by prion
Mad cow disease (in cows), Creutzfeldt-Jakob disease in humans from transplanted nerve tissue, contaminated surgical instruments or meat from infected cows
Cause neurological damage

61
Q

How do prions cause neurological damage

A

induce abnormal folding of specific normal cellular proteins in the brain from alpha protein (normal) to beta sheet (abnormal)

62
Q

Prion classification

A

Nonliving, infectious proteins

USC Microbiology 1 (9 decks)

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