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Gastrointestinal tract > Microbiology/Immunology > Flashcards

Microbiology/Immunology Flashcards

1
Q

What is dysentry? Two main bacterial causes? (include their gram stain and respiration)

A

Blood and mucus in diarrhoea.

Shigella dysenteriae and enteroinvasive E.coli. Both gram - rods that are facultative anaerobic

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2
Q

What is the most common cause of food borne diarrhoea? Whats it’s mechanism?

A

Salmonella, uptake via M cells, infects eptithelial cells then invades lamina propria to cause inflammation

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3
Q

What is the most common cause of travellers diarrhoea? What is its mechanism?

A

ETEC, attaches via fimbriae and release HL and HT enterotoxins

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4
Q

What causes antibiotic associated diarrhoea (pseudomembranous colitis) and how?
What happens in it?

A

Clostridium difficile, it normally lives in gut and antibiotics inhibit other gut flora allowing it to multiple.
Produces cytotoxic toxins which cause cell death, inflammation and necrosis

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5
Q

What are the two main causes of hemorrhagic colitis? What can it lead to?

A

EHEC and shigella dysenteriae

Haemorrhagic uremic syndrome

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6
Q

How does EPEC cause diarrhoea?

A

Adheres initially via plasmid mediation.
Then chromosomal genes produce Bfp, ignition and Tir which allows attachment efacement onto the microvilli to occur, disrupting them.

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7
Q

When do we use antibiotics to treat diarrhoea? Which antibiotic is commonly used?

A

Protozoa, pseudomembranous colitis, severe shigella, cholera, if gone systemic, immunocompromised patients.
Use metronidazole

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8
Q

What are the 4 main phyla of bacteria that live in the GIT?

A

Firmicutes
Bacterodetes
Actinobacteria
Proteobacteria

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9
Q

What 2 signals are needed to activated IL-1?

A

Signal from a TLR to produce Pro-IL-1B
Signal from NLR–>inflammasome that cleaves caspase-1.
Caspase-1 then cleaves to create active IL-1

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10
Q

How do macrophages release IL-1? What are some of IL-1’s functions once released?

A

By undergoing pyroptosis (dying therefore releasing it)

  • neutrophil activation which clear up pathogen
  • fever
  • B and T cell activation
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11
Q

How do inflammasomes contribute to metabolic syndrome?

A

Obesity is low grad inflamm disease as adipocytes die.
Causes inflammasome activation
IL-1 causes insulin resistance, which in long term can cause death of liver and pancreatic cells (eventual type 2 diabetes)

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12
Q

Where are M cells located and what do they do?

A

Located in epithelium above Peyers patches in SI.

Deliver antigens to the APC in the PP.

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13
Q

How do we home activated T and B cells back to the mucosa?

A

Dendritic cells induce addressin a4B7 which binds to integrin MAdCAM1 on mucosal epithelial cells

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14
Q

Which antibody do B cells committee to produce in the SI and why?

A

IgA as it neutralises gut pathogens and their toxins

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15
Q

What are the direct and indirect effects of the microbiota on the gut immune system?

A

Direct: Blocks binding sites and produces bacteriocins
Indirect: Cause PAMP signalling which:
- Production of mucus
- Proliferation of crypt enterocytes: Antimicrobials and immunomodulators
- PAMPs on IEL, LTi and NK-22 cause IL-22 release which is involved in epithelial integrity and antimicrobial defence

  • The short chain fatty acids cause inactivation of Nf-KB
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16
Q

What T cells does the microflora produce vs pathogens?

A

DC PRR activated by microbiota induce tolerogenic T cells- TH2 and Treg (physiological inflammation)
DC PRR activated by pathogens induce inflammatory T cells- TH1 and TH17 (pathologenic inflammation)

17
Q

What does obesity do to gut microbiota diversity and wha are the consequences of this?

A

It decreases diversity

  • Means more insulin resistant
  • More serum triglycerides
  • Higher cholesterol
18
Q

What is the pathogenesis of hepatitis from?

A

The immune response

19
Q 
What family does Hep A belong to?
Acute/chronic
What +/-, ss/ds, DNA/RNA, enveloped
Site of primary replication
Where do they come from and what is their route of transmission?
A 
Picornaviridae 
Acute
\+ ss RNA
Non enveloped
Liver 
From faeces and transmit via faecal-oral route
20
Q 
What family does Hep E belong to?
Acute/chronic
What +/-, ss/ds, DNA/RNA, enveloped
Site of primary replication
Where do they come from and what is their route of transmission?
A 
Hepeviridae 
Acute
\+ ssRNA
Non enveloped
They dont know
From faeces and transmit via faecal-oral route
21
Q

What does +IgM and +IgM vs +IgM and -IgM mean in terms of Hep A/E infection?

A

If IgG and IgM + then in the middle of acute hepatitis

If IgM- then are a while past the acute infection and are immune or have been vaccinated (in case of hep A)

22
Q

What does HBeAg and Anti–Hbe Ig represent?

A

HBeAg shows He B virus is replicating in liver.

Anti-Hbe Ig shows no longer replicating, goal of treatment.

23
Q

What are some Hep B antivirals?

A

IFNa and nucleotide analogues

24
Q 
In reference to Hep B is it:
Acute/chronic
What +/-, ss/ds, DNA/RNA, enveloped
Site of primary replication
Where do they come from?
A 
Chronic
ds DNA (incomplete)
Outer envelope and inner nucleocapsid core
Liver
Route via blood/body fluids
25
Q 
In reference to Hep C is it:
Acute/chronic
What +/-, ss/ds, DNA/RNA, enveloped
Site of primary replication
Where do they come from?
A

Chronic
+ ss RNA
Outer envelope and inner nucleocapsid core
In liver cell, but outside nucleus as has own RNA polymerase
Blood/body fluids

26
Q

What % of Hep C infected will be chronically infected?

A

70%

27
Q

What are lice?

What 3 species are there and which area do they affect?

A 
Insects
Pediculus Humanis (body), P capitis (head) and P. Pubis (pubic area)
28
Q

What are Mites (scabies)?
Species name?
Where do they invade?

A

Arachnoids
Sarcoptes scabiei
Tunnels into epidermis

29
Q

What are ticks?
Species name?
Which gender is the issue? What is the main issue they cause?

A

Arachnoid
Lxodes Holocyclus
Female causes paralysis

30
Q

What is Entamoebe histolytica?
Where does it invade?
What can be some consequences?

A

Amoebe
Tissue of the colon
Leads to amoebic dysentry and can also lead to liver abscesses

31
Q

What is Giardia intestinalis? What do they cause?

A

Flagellate

Causes diarrhoea

32
Q

What is toxoplasma gondii?
Does it show symptoms?
How can it be dangerous in pregnancy?

A

Obligate intracellular parasite
Not in people who aren’t immunocompromised
If get for first time during pregnancy then can cause abortion or retardation

33
Q

What is Enterobius vermicularis (pinworm)

How does its cycle work?

A 
A nematode 
Ingested
Larve hatch SI
Adult chill in LI
Out to perianal at night to lay eggs
Scratch
34
Q

What is Ascaris lumbricoides?
Describe its life cycle
What can be a complication?

A

A nematode
Embyronisation occurs in the soil
Ingested
Finishes maturing and stored in duodenum
Pneumonitis or obstruction as they can migrate in blood

35
Q

What is strongyloides stercoralis?

Describe life cycle

A

Nematode
infective enetrates through skin.
Via blood to trachea/pharynx
Swallowed and to SI where they mature to adults
Lay eggs which hatch
They can then auto infect
Or be released into env. through stools where they become infective larvae

36
Q

What is schistosoma mansoni?
Describe life cycle
What are some complications if bad infection?

A

Trematode (fluke)
Egg–> larvae in snails
Penetrates skin
Through blood to liver–> adult
To mesenteric veins and lay eggs
Eggs travel via portal veins, excreted in faeces
Complications from immune response such as itch, hepatomegaly, splenomegaly as eggs land there from blood

37
Q

What is echinococcus granulosus?
What kind of host are humans?
What are the cysts called and what problems can they cause?

A

Tapeworm
An accidental intermediate host, they aren’t needed and cant replace the definite host of dogs
Hydatid cysts, can lodge in tissues esp. liver or lungs

38
Q

What can all worms be treated by?

A

Anthelmintics which stun/kill them expelling them from body

39
Q

What is Taeniasis?
What kind of host are humans?
Where are the cysts made and what are the risks of the cysts?

A

Tapework
Definite or intermediate hosts with pigs
Can invaded into SI wall and make cysts which can get into neural tissue

Gastrointestinal tract (6 decks)

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