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PHA112 > Microbiology 8 > Flashcards

Microbiology 8 Flashcards

1
Q

lower respiratory diseases killed how many people in 2016?

A

3 million

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2
Q

diarrhoeal diseases killed how many people in 2016?

A

1.4 million

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3
Q

in developed countries ….% of hospital patients encountered …. infection

A

5-12

nosocomial

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4
Q

risks are determined by individual susceptibility and are multifactorial.

give examples of these?

A
  • genes
  • previous exposure
  • age
  • chronic illness
  • medicines
  • surgery
  • malnourishment
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5
Q

what is the highest cause of deaths in high-income countries?

A

ischaemic heart disease

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6
Q

what is an endemic?

A

an infection present in a population which is maintained constantly with no external input

e.g. chickenpox

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7
Q

what is an epidemic?

A

an infection which rapidly spreads in a short time period (usually < or equal to 2 weeks/less)

e.g. ebola

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8
Q

what is a pandemic?

A

an epidemic which has spread across a large region (multiple continents/ globally)

e.g. spanish flu, black death, 2009 H1N1 influenza pandemic

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9
Q

what is pathogenicity?

A

ability of a pathogen to produce an infectious disease in an organism

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10
Q

what is virulence?

A

relative degree of damage done by a pathogen/ degree of pathology caused by a pathogen

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11
Q

where does colonisation of a niche happen?

A

in host

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12
Q

what is immunoevasion?

A

evasion of hosts immune response

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13
Q

what is immunosuppression?

A

inhibition of hosts immune response

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14
Q

where do pathogens obtain nutrients from?

A

host

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15
Q

what are obligate pathogens?

A

a microorganism that has to cause disease to be passed between hosts and must infect host in order to survive

e.g mycobacterium tuberculosis

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16
Q

what is an opportunistic pathogen?

A

a commensal/non harmful microorganism that can cause disease when hosts resistance is low

e.g. Candida albicans, staph aureus, pseudomonas aeruginosa

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17
Q

commensal microorganisms?

A
  • part of normal flora
  • usually non-pathogenic
  • some = pathogenic but unable to enter disease process
  • lack ability to attach suitable surface
  • held in check by other organisms
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18
Q

how can commensal microorganisms prevent disease?

A
  • block attachment sites

- produce antimicrobial products as part of normal metabolism

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19
Q

when can commensal microorganisms cause disease in humans?

A
  • microbial balance is upset (after antibiotic treatment)
  • microbes get to places where shouldn’t be (blood stream infections)
  • host community compromised
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20
Q

what are the waterborne sources of disease?

A
  • cholera
  • typhoid
  • legionella
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21
Q

what are the food borne sources of disease?

A
  • salmonella
  • campylobacter
  • e.coli
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22
Q

what are sources of disease on surfaces?

A

norovirus form

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23
Q

what are the sources of disease in soil?

A
  • clostridium botulinum

- c tetani

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24
Q

what are the sources of disease in bacteria?

A
  • anthrax
  • e.coli
  • plague
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25
Q

what are the sources of disease in parasites?

A

toxoplasmosis

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26
Q

what are the sources of disease in viruses?

A
  • avian influenza
  • CCHF
  • ebola
  • Rift Valley fever
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27
Q

what are the other sources of disease in animals?

A

BSE

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28
Q

what are zoonoses?

A

infectious diseases that can = naturally transmitted between non-humans (usually vertebrates) and humans

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29
Q

what can animals act as?

A

a reservoir (place where agents live)

contribute to development of pandemics

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30
Q

what are the occupations that come in close contact with animals/animal products?

A
  • farmers
  • tanners
  • slaughterhouse workers
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31
Q

what other occupations are at a high risk of exposure to infectious agents?

A
  • laboratory

- healthcare

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32
Q

what animal viruses can humans contract?

A
  • bird flu
  • H5N1
  • H1N1 swine flu
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33
Q

what is antigenic shift?

A

combination of 2/more different strains

  • prod new form of virus which shows mixture of surface antigens
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34
Q

what is antigenic drift?

A

accumulation of mutations within antibody binding regions

  • reduces effectiveness of immune system
35
Q

when was koch’s postulates first described?

A

1890

36
Q

what is the proof available for koch’s postulates?

A
  • plague
  • anthrax
  • diphtheria
  • cholera
  • typhoid
37
Q

when is koch’s postulate less evident?

A
  • condition = chronic / minor
  • condition has multiple causes/pathogens = non - culturable
  • no suitable animal model of infection
  • agents causing pneumonia, wound infection, UTIs, septicaemia
38
Q

koch’s postulate process

A
  1. microorganism must = found in abundance in all organisms suffering from disease (not in healthy organisms)
  2. microorganism = isolated from diseased organism and grown in pure culture
  3. cultured microorganism should cause disease when introduced into healthy organism
  4. microorganism re-isolated from inoculated, diseased experimental host & found as being identical to original specific causative agent
39
Q

updated koch: molecular postulated?

A
  • identify gene responsible
  • show that gene is present in disease causing strains of bacteria
    (not present in avirulent strains)
  • show that disrupting gene reduces virulence
  • introduce cloned gene into avirulent strain
    (should confer virulence)
    (gene expressed in vivo)
  • specific immune response to gene protects
40
Q

what 3 stages can disease be broadly split into?

A
  • transmission and exposure
  • attachment and invasion
  • colonisation and damage
41
Q

describe the disease process?

A
  1. pathogen exposure
  2. skin/mucosa adherence
  3. epithelia invasion
  4. colonisation and growth
  5. invasiveness (further growth at original/other sites) & local/systemic toxicity
  6. tissue damage and disease
42
Q

what is transmission?

A

passing of communicable disease from infected host to particular individual/group, regardless of whether other individual was previously infected

43
Q

give an example of vertical transmission?

A

mother to child e.g. HIV

44
Q

give an example of horizontal transmission?

A

person to person transmission e.g. chlamydia

45
Q

what is vehicle borne transmission?

A

transmission through inanimate object

46
Q

what is vector borne transmission?

A

transmission through another organism e.g. malaria

47
Q

what disease can be vertical, horizontal or vehicle borne?

A

HIV

48
Q

what routes does horizontal exposure tend to be?

A
  • inhalation
  • ingestion
  • contact
49
Q

what does successful exposure depend on?

A
  • microbe count: more = better
  • airborne: size, density, surface features
  • waterborne: density, surface features hydrophobicity
  • contact: environmental persistence (imp in hospital acquired infections)
  • distribution on host: into cuts, digestive system, GU system, lungs..
  • vectors
50
Q

what does attachment and invasion depend on?

A

surface break / on active microbial procedures

51
Q

virulence factors play an important role in what?

A
  • pili/adhesins (aid attachment to cells)
  • capsules (resist phagocytosis)
  • enzyme production
52
Q

what does a biofilm comprise of?

A

any group of microorganisms in which cells stick to each other and to surface

53
Q

are biofilms naturally occuring?

A

yes

54
Q

an estimated … of infections involve biofilms

A

80%

55
Q

what do biofilms increase?

A
  • average hospital stay

- resistance to treatment

56
Q

what are biofilms especially important in?

A

CF

  • form within lungs
57
Q

what does growth in tissues require?

A

cells to resist host responses

  • potentially neutralise e.g. enzymes, capsules
58
Q

what does growth also need?

A

appropriate nutrients

  • some tissues have limited (e.g. iron) / specific nutrients which slow/enhance microbial growth
59
Q

host cell death happens as a result of..

A
  • damage
  • toxin accumulation
  • enzymatic digestion
60
Q

what pathogenicity factors play an important role in colonisation and damage?

A
  • bacterial toxins
  • exotoxins
  • endotoxins (LPS)
  • capsule
  • bacterial enzymes
61
Q

microbial toxins promote infection by…

A

damaging tissue

through endotoxins (LPS) and exotoxins (secreted toxins)

62
Q

endotoxins are part of the bacterial cell membrane.

what can they lead to?

A
  • septic shock

- highly controlled in sterile pharmaceutical products

63
Q

clostridium difficile produces two main toxins.

what are they?

A
  • toxin A (enterotoxin)
  • toxin B (cytotoxin)

play important role in disrupting gut epithelia

64
Q

give an example of another toxin that has found other uses?

A
  • botulinum toxin among most powerful

- estimated LD50 of 1.3-2.1 ng/kg IV or IM

65
Q

what are the 3 general types of microbial exotoxins based on effect?

A
  • cytotoxins (kills cells)
  • neurotoxins (interfere with normal nerve impulses)
  • enterotoxins (affect cells lining GI tract)
66
Q

what can these microbial exotoxins be further divided into?

A
  • Type 1 - superantigens
  • Type 2 - membrane disrupting toxins
  • Type 3 - protein modification
67
Q

Type 1 exotoxins?

A
  • cause intense immune response
  • due to nonspecific cytokine release from host cells

produced by some S.AUREUS strains

68
Q

Type 2 exotoxins?

A
  • disrupt phospholipid bilayer

- make protein channels in PM e.g. cholera toxin

69
Q

Type 3 exotoxins?

A
  • e.g. diphtheria, shiva toxin
  • inhibit synthesis
  • tetanus toxin cleaves protein involved in neurotransmitter release
70
Q

microbial endotoxins are heat stable.

what does this mean?

A

difficult to remove from pharmaceutical preparations

71
Q

what portion of LPS is lipid A part of?

A

toxin portion

72
Q

what is lipid A responsible for? and how?

A

fever associated with G bacterial infections

  • when G cells digested, endotoxins released - causes fever
  • if immune system acting on high G- bacterial load, large release of endotoxins trigger septic shock
  • antibiotics initially cause fever / shock due to endotoxin release
73
Q

what do haemolysins cause

A

red blood cell lysis by forming pores in plasma membranes

74
Q

what are haemolysins?

A

most = proteins

some are lipid biosurfactants

75
Q

bacteria can be classified on basis of haemolysis.

give the 3 classifications?

A
  • ALPHA - oxidise iron (S. pneumoniae)
  • BETA - ruptures RBC (S. pyogenes)
  • GAMMA (non-haemolytic)
76
Q

what can haemolysis lead to?

A

haemolytic anaemia

- bone marrow can’t produce RBC fast enough to replace loss

77
Q

mycoses are diseases caused by fungi

give properties of mycoses?

A
  • persistent (chronic)
  • localised/ systemic
  • from inhalation of fungal spores
  • most common in immunocompromised patients or those taken antibiotics
78
Q

give 3 examples of what fungal diseases include?

A
  • athletes foot
  • thrush
  • aspergillosis
79
Q

athletes foot

A
  • irritation, dry, inflamed skin with localised pain

- caused by species of trichophtyon, epidermophyton, microsporum

80
Q

thrush

A

caused by Candida albicans

81
Q

aspergillosis

A
  • caused by aspergillus fumigatus

- invasive in immune compromised patients

82
Q

viral diseases can cause communicable and non-communicable diseases.

give examples of communicable diseases?

A
  • herpes
  • HIV
  • influenza
83
Q

give examples of non-communicable diseases?

A
  • HPV -> cervical cancer
  • human adenovirus Ad-36 -> obesity
  • mouse mammary tumour virus -> human breast cancer

PHA112 (37 decks)

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