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Medicine yr1 > FOUND-viruses and bacteria > Flashcards

FOUND-viruses and bacteria Flashcards

1
Q

what are the different modes of transmission and examples of diseases transmitted this way?

A
  • Respiratory-TB/ COVID
  • oral/faecal- polio
  • Contact-(skin-skin/mucous/mucous)
  • blood-borne-HIV
  • Vector-mosquitos-malaria
  • vehicle-non-living thing
  • nosocomial-contracted in hospital
  • zoonotic-viruses
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2
Q

what is the approx size of bacteria?

A

-1000 x2-3000nm

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3
Q

what is the function of flagella?

A

movement and adhesion

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4
Q

what is the function of pili?

A

adhesion, conjugation (transfers genetic material to another through direct contact) and movement found in many gram negatives

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5
Q

what is the capsule of bacterias function?

A

adhesion
protection

contribute to disease

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6
Q

what is the role of chromosomes in bacteria?

A

contain genetic code

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7
Q

what is the role of plasmids?

A

contain some genes-can confer advantage-antibiotics

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8
Q

what is the difference between gram-positive and gram-negative?

A

gram-positive

  • thick peptidoglycan layer
  • no LPS

gram-negtaive

  • lipopolysaccharide and proteins
  • thin peptidoglycan layer
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9
Q

what does LPS act as when released?

A

an endotoxin

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10
Q

what are examples of endospore-forming bacteria?

A

Bacillus

  • B. anthracris -anthrax
  • B. cereus -food poisoning

Clostridium (strict anaerobes)

  • C. botulinum- botulism
  • C. difficile-diarrhoea
  • C. perfringens- gas gangrene
  • C. tetani- tetanus
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11
Q

what is virulence?

A

the relative ability of a pathogen to cause disease in the host

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12
Q

what is an opportunistic pathogen?

A

normally harmless but can cause disease due to lowered host immunity

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13
Q

what is the incubation period?

A

between time of infection and appearance of symptoms

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14
Q

what are the two types of toxins produced by bacteria?

A 
exotoxins
endotoxins (LPS)
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15
Q

Explain the steps in bacteria pathogenicity

A

-exposure to pathogens
-adherence to skin or mucosa
-invasion through epithelium
-colonisation and growth
(production of virulence )
-toxin effects local or systemic
-or invasiveness-further growth at original site and distant site
-tissue damage/ inflammation/ disease

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16
Q

what are the 2 types of infection response?

A

extracellular

intracellular

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17
Q

describe extracellular infection response

A
  • main response is antibody response

- also innate immunity-phagocytosis by neutrophils, monocytes and tissue macrophages

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18
Q

describe intracellular infection response

A

specific cell-mediated responses

-eg macrophage activation

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19
Q

are streptococcal species of bacteria gram positive or gram negative?

A

spherical gram + bacteria

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20
Q

what can streptococcus species can be classified into?

A

either alpha-haemolytic or beta-haemolytic depending on ability to haemolyse RBCs

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21
Q

what can beta-haemolytic streptococci be further divided into?

A

groups A-T based on polysaccharide capsular structure- Lancefield serotyping

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22
Q

what are the 3 main clinically important species of streptococci?

A

-S. pyogenes- group A
(strep throat, scarlett fever, toxic shock, necrotising fasciitis)
-S. agalactiae- group B
(neonatal sepsis and meningitis)

-S.pneumoniae
(lobar pneumonia)

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23
Q

describe the features of streptococcus pneumoniae

A
  • gram positive alpha-haemolytic non-motile coccus

- over 90 capsular serotypes

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24
Q

how is DNA organised in bacteria?

A

singular circular chromosomes and plasmids

not contained within nucelus

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25
Q

what are the features of gram positive bacteria?

A
  • phospholipid bilayer
  • thick peptidoglycan layer
  • no extra phospholipid bilayer with lipopolyscaccharide
26
Q

what are some examples of gram-positive bacteria?

A
  • staphlococcus aureus (cocci)
  • stretococcus pyogenes (cocci)
  • clostridium sporogenes (rod)
27
Q

what colour does gram positive bacteria stain?

A

blue/ purple

28
Q

what are the features of gram negative bacteria?

A
  • phospholipid bilayer
  • thin peptidoglycan layer
  • extra phospholipid bilayer-integration of lipopolysaccharide
29
Q

what are some examples of gram negative bacteria?

A
  • neisseria gonorrhoeae (cocci)
  • pseudomonas aeruginosa (rod)
  • haemophilus influenzae (rod)
30
Q

what colour does gram negative bacteria stain?

A

red/pink

31
Q

what is a virus?

A

a small, infectious, obligate intracellular parasite

32
Q

what is a parasite?

A

an organism that benefits at the expense of the host

33
Q

what do viruses need to do to function?

A

can only function after they are replicated in a cell as they are obligate molecular parasites

34
Q

how do viruses cause disease?

A

viruses make mRNA that can be translated by host ribosomes-they then hijack host protein synthesis machinery

35
Q

what is a virion and what is their function?

A

virus paticle that protects the genome as it is transmitted from one host to another

36
Q

why is it important to be able to classify viruses?

A

classification makes possible predictions about the properties of a virus
-particularly important when a new virus is identified

37
Q

what properties are used for classification of viruses?

A
  • size of virion and capsid
  • presence or absence of an envelope (membrane)
  • symmetry of protein shell (capsid)
  • nature and sequence of nucleic acid (virus genome)
  • symptoms
  • routes of transmission
38
Q

what are the steps in virus infection and replication?

A
  • infecting virus attaches to host cell
  • capsid penetrates host cell
  • capsid uncoats- is shed
  • repication-synthesis of mRNA (direct or via host machinery) synthesis of viral protein for new capsid, synthesis of viral nucleic acid
  • assembly-capsids from around nucleic acid
  • viral nuclic acid is released by cytolysis
39
Q

how is bacteria replicated?

A

binary fission

40
Q

are virus genomes DNA or RNA?

A

can be either

41
Q

are virus genomes single or double stranded?

A

can be either

42
Q

if the viral genome is single-stranded is it +ive or -ive sense?

A

can be either

43
Q

is viral genome linear or circular?

A

can be either

44
Q

is viral genome single or segment?

A

can be either or more than 1

45
Q

why do viral genomes have to be abLe to make mRNA?

A
  • to be translated by ribosomes to make viral proteins

- to make new virus particles-virions

46
Q

what is Baltimore classification?

A
  • based on mRNA as the common theme

- viruses (genomes) classified depending on how they make mRNA (+sense)

47
Q

what are the different methods of viral transmission?

A
  • respiratory
  • oral/faecal
  • blood borne viruses
  • other bodily fluids
  • arboviruses (vector)
48
Q

define the infectious period

A

the period when you are releasing virus which can infect others

49
Q

define the incubation period

A

period in between when you are first infected with the virus, the virus is replicating

50
Q

what’s the difference between droplet and airborne transmission?

A

droplet infection-coughs and sneezes can spread droplets of saliva and mucus
(more than 5 microns)

airborne transmission-tiny particles, possibly produced by talking, are suspended in the air for longer and travel further (less than 5 microns)

51
Q

what is the basic reproductive number?

A

R0

A means of expressing how many uninfected people can be infected by one infectious person

52
Q

what does R0<1 mean?

A

the infection will generally dies out in the the population

53
Q

what does R0>1 mean about an infection?

A

the infection will be maintained and spread in the population

54
Q

what does a high R0 mean?

A

the virus will spread quickly

55
Q

what is viral pathogenesis?

A

mode of production or development of disease

56
Q

do all viruses cause noticeable disease?

A

no some may be asymptomatic

57
Q

what are systemic infections?

A
  • spread of virus throughout the body multiple organs are infected
  • virus gains access into blood stream (lymph system)
  • extreme rapid virus dissemination throughout the body
58
Q

what is the definition of viraemia?

A

the existence of viruses/ virus particles in the blood stream

59
Q

what is lytic infection?

A

infection as a result of active replication of the viral genome, characterised by making of new viral particles

60
Q

what is latent infection?

A

when virus is in a state of non replication-quiescent state

Medicine yr1 (55 decks)

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