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GI > Microbiology > Flashcards

Microbiology Flashcards

1
Q

H Pylori is often acquired at age ——

Around ——–% of world population infected.

A

Acquired at young age (consequences later in life)

50% of world population infected.

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2
Q

H Pylori - routes of contraction

A

Direct contact, oral-oral, feacal-oral

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3
Q

H Pylori infection increases risk of:

A

Duodenal ulcer, gastritis.
Gastric ulcer.
Gastric carcinoma.
Gastric lymphoma.

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4
Q

Why does H Pylori produce ammonia?

A

To increase the pH and protect itself from highly acidic environments.

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5
Q

How does H Pylori produce ammonia?

A

By producing UREASE

H2O + H+ &raquo_space;» ammonium bicarbonate

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6
Q

Gastroenteritis

A

illness caused by eating foods contaminated with microorganisms, toxins and poisons

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7
Q

Dysentery

A

Inflammation of intestine, causing diarrhoea associated with blood and mucus
(associated with tenesmus - cramping in rectal area)

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8
Q

Dysentery is commonly caused by ——-

A

shigella and campylobacter

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9
Q

Diarrhoea

A

> 3 unformed stools in a day when the subject has taken no laxatives

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10
Q 
Bacillus cereus 
(key points)
A

REHEATING STARCHY FOOD (e.g. rice)
Short incubation (1-6hrs)
Vomiting
Lasts 24hrs

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11
Q 
Staph aureus 
(key points)
A

FOOD LEFT AT ROOM TEMP (milk, meat, fish)
short incubation (1-6hrs)
Lasts 1-2 days

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12
Q

Both bacillus cereus and staph aureus usually cause {upper/lower} GI symptoms.

A

upper (e.g. vomiting)

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13
Q

Staph aureus has a preformed toxin called ———— causing ———–

A

enterotoxin B causes rapid absorption

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14
Q

Most common cause of food poisoning is ————

A

campylobacter

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15
Q

Campylobacter

key points

A

RAW POULTRY/RAW MILK (unpasteurised)
D&V (may be bloody), abdo pain, fever.
Lasts 2-10 days
**risk of Guillain Barre syndrome.

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16
Q

You are more likely to get ——– from raw chicken than salmonella

A

campylobacter

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17
Q

———— is the most common strain of campylobacter

A

Campylobacter jejuni

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18
Q

Salmonella is serotyped according to ———

A

O-antigen

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19
Q

Salmonella

key points

A 
OUTBREAKS
RAW MEAT, RAW EGG, RAW MILK.
(can be transmitted from reptiles)
D&V (unlikely to be bloody), abdo pain, fever.
Lasts 2-7 days
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20
Q

Shigella

key points

A

CONTAMINATED food/water with lots of HAND CONTACT (salad/sandwiches/raw veg)
BLOODY DIARRHOEA/mucous, vomiting, abdo cramps, fever…
Lasts 2-7 days

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21
Q

Shigella toxin =

A

shiga toxin - type 1 and type 2

TYPE 2 IS WORSE

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22
Q

Shigella toxin - method of action

A

Toxin binds to receptors on renal cells, RBC’s and other cells&raquo_space; inhibits protein synthesis&raquo_space; cell death

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23
Q

E.coli (0157)

A

CATTLE/BEEF, RAW MILK - usually undercooked beef
Rare - outbreaks
BLOODY DIARRHOEA (may have vomiting, abdo pain)
Lasts 5-10 days
**risk of HUS

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24
Q

E.coli toxin =

A

verotoxin

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25
Q

Why do you not give antibodies for E. coli infection?

A

Increases risk of HUS

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26
Q

Verotoxin - method of action

A

binds to enterocytes&raquo_space; inhibition of protein synthesis&raquo_space; cell death&raquo_space; provides verotoxin route to bloodstream&raquo_space; cause death of vascular endothelial cells&raquo_space; clots form within small vessels&raquo_space; clots + verotoxin carried to kidneys&raquo_space; renal cell death&raquo_space; renal failure&raquo_space; HUS

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27
Q

What is HUS?

A

Haemolytic-uremic syndrome
group of blood disorders characterized by low RBCs, acute kidney failure, and low platelets - caused by E. coli infection.
Most < 16 yrs old.

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28
Q

HUS - symptoms

A

Abdo pain, fever, pallor, petechiae (purple spots on the skin due to damaged blood vessels), oliguria.
Bloody diarrhoea but it may have stopped.

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29
Q

Why should antibiotics be avoided in the treatment of food poisoning?

A

Possibly E. coli - risk of HUS
Risk of antibiotic resistance
Illness is usually self-limiting

30
Q

HUS may be precipitated by ———-

A

Antibiotics, antimotility, and NSAIDS.

31
Q

Gastroenteritis + urinary symptoms suggesting kidney involvement =

A

HUS

32
Q

HUS - investigations/management

A

Any patient with bloody stools gets tested
FBC, U&E’s, LFT, urine samples
Lactate dehydrogenase – chemical released from damaged cells

Must notify relevant health boards of any HUS cases.
Treatment is supportive

33
Q

Must notify health protection unit of any —— infections

A

E. coli (0157)

34
Q

———– and ———- infection both result in bloody diarrhoea

A

shigella and E. coli (0157)

*campylobacter may also cause bloody diarrhoea

35
Q

Listeria

key points

A

THE FRIDGE ORGANISM - soft cheeses, deli meats, unpasteurised milk.
Fever, stiff neck, confusion, vomiting - pregnant women and immunocompromised at risk.
Incubation 3-70 days, lasts WEEKS.

36
Q

C. Diff most commonly occurs when ——

A

the patient has been given hospital antibiotics

antibiotics kill normal competitive bowel flora, allowing C. diff overgrowth

37
Q

C. diff can progress to ——-

A

pseudomembranous colitis or bowel perforation

38
Q

Risk of C. diff is increased by ———

A

As well as hospital antibiotics, anything that reduces the acidity of the stomach can increase risk
e.g. PPI’s carry a risk

39
Q

C. diff toxin =

A 
Toxin A (enterotoxin) 
and Toxin B (cytotoxin)
40
Q

What antibiotics increase the risk of C. Diff?

A 
4Cs
Cephalosporin
Ciprofloxacin
Co-amoxiclav
Clindamycin
41
Q

C. diff - symptoms

A

Watery diarrhoea.

Abdo pain and fever.

42
Q

C. diff - treatment

A

Non-severe = Metronidazole oral (10 days).

Severe: Vancomycin oral + Metronidazole IV (10 days).

43
Q

Rotavirus

key points

A

Usually children in nurseries (most common cause of diarrhoea in kids under 3)
Mild, watery profuse diarrhoea (bloody = RED FLAG) - rehydrate
Incubation 48hrs, lasts a week

44
Q

Norovirus

key points

A

CRUISE SHIPS, WARDS, NURSING HOMES (can be contracted from shellfish)
Highly infectious.
Explosive D&V (no blood) - rehydrate
Incubation 48hrs, lasts 1-3 days

45
Q

In gastroenteritis, all stool samples get tested for ————

A

salmonella, shigella, campylobacter, E.coli 0157 and cryptosporidium

46
Q

Gastroenteritis - investigations

A

stool culture, stool microscopy, stool toxin and stool PCR

47
Q

In gastroenteritis,
if suspected bacteria - investigation =
if suspected virus - investigation =
if suspected protozoa - investigation =

A

bacteria = stool culture
( or stool toxin for c. diff or E. coli)
virus = stool PCR
protozoa = stool microscopy (for cysts)

48
Q

In gastroenteritis, do a stool culture if ——– are suspected, and do a stool toxin if —- are suspected.

A

Stool culture = salmonella, campylobacter

Stool toxin = c. diff, E. coli

49
Q

Gastroenteritis - treatment

A

No antibiotics - except to treat c. diff.

Rehydration = key

50
Q

Someone who has been at a BBQ and thought the burgers looked funny

A

E.coli

51
Q

Someone who had been at a Chinese buffet/had reheated a takeaway with rice

A

Bacillus cereus

52
Q

Someone remembers eating a cream cake that had been left out

A

Staph aureus

53
Q

Care home where many of its residents have diarrhoea and some aren’t urinating

A

HUS - E.coli

54
Q

Tropical gastroenteritis - causes

A

Someone travelling + doing one of the following:
Swimming in lakes
Drinking water from local taps
Sexual activity
Insect bites
Did they get vaccinations before they left

55
Q

Acute travellers diarrhoea

A

3 loose stools in 24hrs on the back of travelling (1/3rd have fever also)

56
Q

Acute travellers diarrhoea - causative organism

A

Usually enterotoxigenic e. coli

If returned from cruise ship = noro/rotavirus

57
Q

Acute travellers diarrhoea - management

A

Stool culture
Rehydration
Current travellers = single dose of ciprofloxacin

58
Q

Cholera

A

Drinking water contaminated with faeces
Profuse watery diarrhoea (RICE-WATER STOOLS)
Massive fluid loss
Toxin mediated

59
Q

Enteric fever

A 
Common
Fever, headache, abdo pain (also GI bleeding and perforation)
Either TYPHOID (salmonella typhi - most severe) or PARATYPHOID (s. paratyphi)
60
Q

Enteric fever usually occurs in what scenario?

A

patients who are returning from SE Asia and the Indian subcontinent

61
Q

Enteric fever - clinical findings

A

Abdominal tenderness

Hepatosplenomegaly

62
Q

Enteric fever - management

A

Patients need isolated immediately
If unstable (septic) = IV ceftriaxone
Otherwise use oral ciprofloxacin
Resistant cases = azithromycin in fluoroquinolone

63
Q

Amoebiasis

A

Protozoa - POOR SANITATION
Protozoa lives in cysts&raquo_space; once ingested. emerge. multiply.
Can often cause liver abscesses
Intermittent diarrhoea, upper abdo pain/discomfort, fever, sweats, nausea, headaches

64
Q

Amoebiasis - investigations

A

Stool MICROSCOPY
Abdominal x-ray (for toxin mega colon)
CXR (may show raised right hemi-diaphragm)
May need endoscopy, biopsy

65
Q

Amoebiasis - management

A

Metronoidazole

Paramomycin (used to clear gut lumen of parasites)

66
Q

Giardiasis

A

Protozoa
Affects duodenum/proximal jejunum
Watery, malodourous diarrhoea, bloating, flatulence, abdo cramps, weight loss

67
Q

Giardiasis - investigation

A

Stool microscopy for cysts

PCR in developed countries

68
Q

Giardiasis - treatment

A

Metronidazole/Tinidazole

69
Q

Helminth Infections

A

Parasitic infection

Associated with eosinophilia

70
Q

Parasite contracted from swimming in lake Malawi

A

Schistosomiasis (Flukes)

71
Q

Parasite contracted from eating undercooked meat

A

Tape worms (Cestode)

72
Q

Helminth Infections - diagnosis

A

Usually diagnosed by the passage of adult worm or eggs in the stool

GI (9 decks)

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