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microbiology > lecture 5) clinical microbiology 1 > Flashcards

lecture 5) clinical microbiology 1 Flashcards

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Biology 101 flashcards
1
Q

name 4 requirements for a disease

A

portal of entry
avoid host defences
establishment
damages host

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2
Q

what is characteristic about the main portals of entry?

A

they are lined with mucous membranes

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3
Q

what is mucuous and what is its importance?

A

liquid solution
composed of glycoproteins
retains moisture

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4
Q

what are mucous membranes protected with?

A

hair
skin
washing secretions
cilia

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5
Q

what are the main roles of mucous membranes?

A

protective covering
resists penetration
traps microbes

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6
Q

what are mucous membranes bathed in?

A

antimicrobial secretions

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7
Q

what is the main enzyme in antimicrobial secretions?

A

lysozyme

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8
Q

what type of bacteria is lysozyme?

A

gram positive

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9
Q

what does lysozyme do?

A

breaks glycosidic bonds in peptidoglycan

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10
Q

mucous contains MALT. what is MALT?

A

mucosal associated lymphoid tissue

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11
Q

what are the primary lymph organs?

A

bone marrow

thymus

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12
Q

what are the secondary lymph organs?

A

MALT

lymph nodes

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13
Q

many body fluids are not suitable for bacterial growth. why is this?

A

makes it inhospitable for the pathogen so it cannot cause infection

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14
Q

what is the importance of iron?

A

everything needs iron to live

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15
Q

how do bacteria gain iron from the host?

A

secrete siderophores
rip off iron and hold it
when this happens the skin becomes slightly acidic

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16
Q

what is the bacterial growth inhibitor found in breast milk?

A

lactenin

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17
Q

what makes lactenin a bacterial growth inhibitor?

A

it is selectively bactericidal

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18
Q

what are antimicrobial peptides?

A

peptide produced by bacteria that are lethal to closely related bacterial species

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19
Q

what do antimicrobial peptides do?

A

produced by bacteria
destroy the membrane
tamper with DNA and RNA

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20
Q

what makes antimicrobial peptides so selective?

A

always carry more of a negative charge on their membranes that eukaryotic cells
creates an electrostatic attraction

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21
Q

describe the antimicrobial peptide sakacin

A

produced by lactobacilli (eg liseria, gram positive)

some have been engineered for mass food production

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22
Q

describe the antimicrobial peptide colicin

A

produced by E.coli
used in polymixin antibiotics
LAST resort of antibiotics as they cause terrible collateral damage

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23
Q

names the defensins of the respiratory tract

A

beta defensins

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24
Q

give an example of a beta defensin found in the respiratory tract

A

cathelicidin

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25
Q

what are defensins?

A

cysteine rich cationic proteins that act as defensive proteins

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26
Q

what is cathecilidin also known as?

A

LL37

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27
Q

what cells produce cathecilidin?

A

neutrophils

epithelial cells

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28
Q

what is the mode of function of cathecilidin as a beta defensin in the respiratory tract?

A

have an ampithatic structure (hydrophobic and hydrophillic regions)
hydrophobic region interacts with lipids
hydrophillic regions come together
unordered structure becomes ordered which impacts pore formation

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29
Q

what does the stomach secrete to make the pH 2?

A

gastric acid

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30
Q

what bacteria has been found in the stomach to have links with causing stomach ulcers?

A

heliobacter pylori

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31
Q

what do the intestines secrete?

A

IgA
pancreatic enzymes
bile
GALT (gastrointestinal associated lymphoid tissue)

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32
Q

what sort of movement is carried out by the intestines?

A

peristalsis

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33
Q

where are the paneth cells found?

A

crypts of liberkun

34
Q

what enzyme do paneth cells secrete?

A

lysozyme

35
Q

what type of defensins are found in the GI tract?

A

alpha defensins

36
Q

what makes the alpha defensins in the GI tract different to the beta defensins in the respiratory tract?

A

open-ended
argenine and cysteine residues
3 pairs of intramolecular disulphide bonds giving them a different secondary and tertiary structure

37
Q

what is the major difference between gram positive and gram negative bacteria?

A

gram negative have an outer phospholipid bilayer whereas gram positive bacteria have a thicket peptidoglycan cell wall

38
Q

what is present in gram positive bacteria that is a good vaccine target?

A

teichoic acid

39
Q

why is it good to have a good vaccine target?

A

antibiotic resistance is on the rise

40
Q

give 2 examples of gram positive bacteria that have teichoic acid

A

C. diff

S. aureus

41
Q

what was the first surface protein found in gram positive bacteria?

A

protein M

42
Q

what makes M protein a good target?

A

protrudes cell wall therefore good attachment

43
Q

give an example of a gram positive bacteria that has M proteins

A

Strep. pyogenes

44
Q

what acid in gram positive bacteria prevents the action of many antibiotics? give an example of a bacteria that has this acid

A

mycolic acid

TB

45
Q

what does lipid A do in gram negative bacteria?

A

anchors LPS

46
Q

if lipid A anchors the LPS, what happens?

A

heightened reaction

47
Q

what type of toxin is lipid A?

A

endotoxin

48
Q

what antigen is found in gram negative bacteria that is very variable, used in typing and that is recognised by the immune system?

A

O antigen

49
Q

what is the name for a structure found in gram negative bacterial cell walls that is composed of polysaccharised and proteins?

A

glycocalyx

50
Q

what is the importance of glycocalyx in the cell wall of gram negative bacteria?

A

creates a loose slime layer

highly organised - can make capsules so the bacteria can avoid the host’s immune cells

51
Q

where are flagella and axial filaments found in gram negative bacteria?

A

beyond the cell wall

52
Q

what is the function of flagella and axial filaments?

A

aids movement

53
Q

name an alternative to flagella that are shorted in length

A

fimbrae and pili

54
Q

name a mechanism that the fimbrae and pii use for immune evasion?

A

antigenic variation

change protein in pili

55
Q

what is DNA’s contribution to antibiotic resistance?

A

it has caused it to spread as it has replicated the genes that have evolved to be resistant to antibiotics

56
Q

components of bacterial cell walls can be targets for what?

A

therapeutics

57
Q

what can ribosomes be targets for in bacterial cells?

A

antibiotics

58
Q

what damage do neurotoxins cause?

A

damage to nervous system
cause paralysis
eg. tetnus lock jaw

59
Q

what impacts to enterotoxins cause in the host?

A 
sickness and diarrhoea 
AB toxin (can be both)
60
Q

what impacts do cytotoxims have on the host?

A

cell death

61
Q

neurotoxins, enterotoxins and cytotoxins are all examples of what type of toxins?

A

exotoxins

62
Q

anthrax, diphtheria and vibrio are all examples of exotoxins. what is similar about them?

A

all gram positive
most exotoxins are
very bad news if you have an exotoxin that is gram negative

63
Q

are exo and endotoxins gram negative or positive?

A 
endo = negative
exo = positive
64
Q

where are exo and endotoxins found?

A

endotoxins found on the cell wall

exotoxins found extracellularly

65
Q

what are the structures of exo and endotoxins

A 
exo = polypeptide
endo = LPS complex
66
Q

which are more stable, exo or endotoxins?

A

endotoxins

67
Q

which are weaker, exo or endotoxins?

A

endotoxins are weaker therefore have a larger lethal dose

68
Q

what do endotoxins cause in the host?

A

fever

69
Q

which are more specific, exo or endotoxins?

A 
exo = specific
endo = non-specific
70
Q

name 2 compounds that streptococcus bacteria have to avoid the host’s defences?

A

coagulase

leukocidens

71
Q

what do leukocidens kill?

A

white blood cells

72
Q

what type of toxin are leukocidens?

A

cytotoxins

73
Q

what group of bacteria produce leukocidens?

A

staph and strep

74
Q

what does coagluse do?

A

causes fibrin blood clots in host

75
Q

what makes strep more virulent than staph?

A

strep produces coagulase

76
Q

what is the impact of antibiotics on gut microbiota?

A

antibiotics disturb the gut microbiota

77
Q

if the gut microbiota is disturbed when using antibiotics to treat C.diff, what is the outcome?

A

diarrhoea

78
Q

what makes a pathogen established in a host?

A

surface of the bug interacts with the host

79
Q

what nearly always causing adhesion of the bug to the host?

A

proteins or carbohydrates or both (glycoproteins)

80
Q

name a structure in bacteria that helps with adhesion

A

pili

81
Q

what do pili do to help adhesion?

A

help bacteria attach and penetrate as they attach to receptors on the host’s surface

82
Q

how do pili retract and what impact does this have on the bacteria when they are trying to establish themselves in the host?

A

retract via motors

bring bacteria closer to the host

microbiology (17 decks)

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