How microbes cause disease Flashcards

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1
Q

what do microbes need to do to survive

A

adherance/colonisation
resist/avoid defence
persist and grow
exit&transmit to new host

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2
Q

what is the period with vague symptoms before illness called

A

prodromal

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3
Q

where do pathogens want to reach and how do they get there

A

sterile body sites, breach barriers eg BBB, skin, mucosal membrane

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4
Q

who competes with pathogens

A

natural flora

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5
Q

what chemicals do tears, saliva and mucus have in them which is antibacterial

A

lysozymes

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6
Q

what other ways do we get rid of toxins/pathogens

A

cilia/urinary flushing/antimicrobial FAs in skin, mucus and phagocytes in lungs

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7
Q

bacteria use more than one adherance mechanisms to stick to the host. give some examples

A

pili/fimbriae
outer membrane proteins eg adhesin&invasin

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8
Q

where does e coli keep its adhesin

A

tip of the pili

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9
Q

what are biofilms made of, what are they, give an example of a biofilm in action

A

slime layer, (Extracellular polymeric substances) polymer EPS, pseudonomas in CF - opportunistic infection

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10
Q

how else that pili and fimbriae can pathogens adhere to host cell

A

via host ECM
Internalins Listeria monocytogenes bind E-Cadherin and C-met
- M proteins Strep. pyogenes bind to receptor on respiratory mucosa

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11
Q

what are the two main problems with biofilms

A

avoiding host immunity
resistance to antibiotics

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12
Q

what do bacteria use to form lesions

A

degradative enxymes

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13
Q

what do degradativeenzymes do and not do

A

mess up tissue - hyaluronase and collagenase
do not kill cells

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14
Q

what are the two types of invasion into host cells

A

trigger zipper

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15
Q

who uses trigger and who uses zipper

A

T:salmonella, shigella
Z: listeria

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16
Q

what is the complement

A

part of innate immune system 30 circulatory proteins

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17
Q

what are the 3 things the complement does

A

opsonisation - tag path with IGG - cleared by pahogcytes
membrane attack complex - hole in bacterial membrane - lysis
enhancing inflammation - mast calls attract phagocytes to the area

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18
Q

what is in lysosomes

A

NO, H2O2

19
Q

which cells have Fc receptors

A

almost all leukocytes

20
Q

how does a bacterail capsule lead to evasion of phagocytosis

A

prevents opsonisation

21
Q

how does Staph aureus avoid phagocytosis

A

binds to Fc region of antibody so the antibody can’t bind to phagocyte

22
Q

what’s the test for Staph aureus

A

catalase test - bubbles when you put H2O2 on it bc catalase turns it into H20 and O2

23
Q

what is the name of the pathogens that steal iron form the host

A

siderophores

24
Q

what is the commensal and how does it normally live

A

one organism benefits from the other and teh other is unaffected. Normal flora of the gut

25
Q

what is virulence

A

quantatitive ability of a pathogen to cause disease

26
Q

what are protozoae; give examples of parasitic protozoic diseases

A

unicellular EUKARYOTES eg malaria, leishmanaisis, Chagas, trypanosomiasis, cryptosporidiosis

27
Q

what are the shapes of different bacteria

A

cocci - spherical
vibrio - spiral tail
bacillues - rodlike

28
Q

what stain is used to identify bacteria? What colour do they go

A

Gram stain
gram-ve pink
gram+ purple

29
Q

describe gram -ve and +ve bacteria

A

+ve thick peptoglycan outer wall, no extra membrane
-ve thin peptoglycan wall, extra membrane

30
Q

how would you identify bacteria

A

microscope - size, shape, colour, gram stain

31
Q

what is the bacteria responsible for syphilis and how do you identify it

A

spirochaetes and darkfield microscopy

32
Q

which stain is needed to identify TB bacteria and what bacteria is it

A

mycobacteria, Ziehl-Nielsen stain

33
Q

how do staphylococci and streptococci look different under a microscope?

A

strepp: chains of spheres
staph: clusters of spheres

34
Q

which two common bacteria are gram +ve

A

staphylococci and streptococci

35
Q

how do you differentiate between staph and strep?

A

catalase test. chuck bleach on it. Stapg is catalase +ve, bubbles form

36
Q

what is staphylococcus aureus

A

bad bacteria, causes abcesses, wound infections, really gross, can go to bones

37
Q

how does staph aureus cause TSS

A

superantigen causing cytokine cascade

38
Q

what do you get in the first stage of syphilsi

A

a gross swelling called a chancre at the site of where the spirochaetes enter the body

39
Q

when do fungi cause a problem

A

in immunocompromised people

40
Q

what is aspergillosis

A

fungal pneumonia only in immunosuppressed

41
Q

what is aspergillosis

A

fungal pneumonia only in immunosuppressed

42
Q

what are some things you need to mention to the lab about a patient

A

travel, symptoms, contact, food, drugs, animals

43
Q

what is a MALD-TOF machine

A

desktop maspec. provides fingerpirnt of all bacteria in the database

44
Q

what is the 1,2,3 of teh complement

A

1)opsonisation - microbes are coated with IGG as a tag for phagocytosis C3B
2)membrane attack complex C5B - hole in bacterial membrane - lysis
3)inflammation enhancement - mast cell attract phagocytes to the area