GI Microbiology Flashcards

1
Q

Gastroenteritis

A

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

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2
Q

Dysentery

A

Inflammation of the intestines, causing diarrhoea associated with blood and mucus

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3
Q

What microorganisms commonly cause dysentery?

A

Shigella

Campylobacter

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4
Q

Bacillus cereus key points

A

Short incubation
Starchy foods - rice
Vomiting

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5
Q

What makes bacillus cereus infection effective?

A

Heat resistant spores

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6
Q

With bacillus cereus, can you get lower GI upset?

A

Yes

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7
Q

Staph aureus key points

A

Foods that have been left at room temperature: meat, milk, fish
Common food is cream cake
Short incubation

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8
Q

Does staph aureus have a pre-formed toxin?

A

Yes

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9
Q

What are symptoms of staph aureus infection?

A

Vomiting
Abdominal pain
Can get lower Gi upset

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10
Q

What are the key points for campylobacter?

A

Most common cause of food poisoning
Medium incubation
Raw poultry, raw milk

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11
Q

What are the symptoms of campylobacter?

A

D&V (may be bloody)
Abdominal pain
Fever

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12
Q

What is there a risk of with campylobacter?

A

Guillain-Barre syndrome

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13
Q

Key points of salmonella

A

Medium incubation
Poultry, meat, raw eggs, raw milk
Can be transmitted from reptiles

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14
Q

In what way does salmonella occur?

A

In outbreaks

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15
Q

What are the symptoms of salmonella infection?

A

D&V - unlikely bloody
Abdominal pain
Fever

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16
Q

What antigen is salmonella serotypes to?

A

O-antigen

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17
Q

Shigella key points

A

Bloody diarrhoea
Produces toxin - type 2 is worse
Contaminated food and water

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18
Q

What foods are worst for shigella?

A

Salads, sandwiches - ones with lots of hand contact

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19
Q

How long is the incubation for shigella?

A

1-7 days

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20
Q

What are the symptoms of shigella infection?

A

Bloody diarrhoea
Vomiting
Abdominal cramps
Fever

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21
Q

How does the shigella toxin work?

A

Toxin binds to receptors on renal cells, RBCs and others
The toxin inhibits protein synthesis
Cell dies

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22
Q

E. Coli key points

A

Bloody diarrhoea
Usually undercooked beef
Produces verotoxin which can cause HUS
Do not give antibiotics - increases risk of HUS

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23
Q

Symptoms of E. coli

A

Bloody diarrhoea
May have vomiting
Abdo pain
Often no fever

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24
Q

How is E. coli spread?

A

Person-person

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25
How does verotoxin work?
Binds to enterocytes, causing inhibition of protein synthesis Death of cells gives verotoxin a route into the blood Then causes death of vascular cells, causing clots to form Verotoxin carried to kidneys, where it kills renal cells and causes renal faiure, resulting in haemolytic uraemia failure
26
What are the symptoms of HUS?
``` Bloody urine Low urine output Abdominal pain Fever Pallor Petechiae Bloody diarrhoea (may have stopped) ```
27
What age range do most cases of HUS occur in?
<16
28
What may precipitate HUS?
Antibiotics, anti-motility drugs and NSAIDs
29
What investigations are done for HUS?
``` FBC U&E LFT Urine samples Lactate dehydrogenase (chemical released form damaged cells) ```
30
Listeria key points
Long incubation Pregnant women and immunocompromised Soft cheeses, deli meats, raw milk
31
Listeria symptoms
``` Fever Stiff neck Confusion Vomiting Sometimes preceded by diarrhoea ```
32
C. diff key points
Hospitals | Broad spectrum antibiotics
33
Does C. diff produce a toxin?
Yes, 2: toxins A and B
34
What are the symptoms of C. diff?
Watery diarrhoea Abdo pain Fever
35
How are non-severe and severe C. diff treated?
Non-severe: metronidazole PO 10 days | Severe: vancomycin PO + metronidazole IV 10 days
36
Rotavirus key points
Children under 3, often in nurseries Diarrhoea, not bloody Rehydration is key treatment
37
What is the most common cause of diarrhoea in children under 3?
Rotavirus
38
Symptoms of rotavirus
Mild, watery or profuse diarrhoea | May progress from fever and vomiting
39
When can rotavirus be severe?
Immunocompromised children
40
Norovirus key points
Cruise ships, wards, nursing homes | Can be contracted from shellfish
41
Symptoms of norovirus
Explosive D&V | Not bloody
42
What are the possible investigations for gastroenteritis?
Stool culture Stool microscopy Stool toxin Stool PCR
43
Which investigation would you do for salmonella and campylobacter?
Stool culture
44
Which investigation would you so for parasitic infections?
Stool microscopy
45
Which investigation would you do for C. diff and E. coli?
Stool toxin
46
Which investigation would you do for norovirus and rotavirus?
Stool PCR
47
In which cases would you give antibiotics for gastroenteritis?
C. diff Immunocompromised patients Some very ill with campylobacter
48
Which microorganism would you suspect for someone who has been at a BBQ and thought the burgers looked funny?
E. coli
49
Which microorganism would you suspect for someone who had been at a Chinese buffet/had reheated a takeaway with rice?
Bacillus cereus
50
Which microorganism would you suspect for someone remembers eating a cream cake that had been left out?
Staph aureus
51
Which microorganism would you suspect for someone at a care home where many of its residents have diarrhoea and some aren't urinating?
HUS - E. coli
52
Cholera key points
Usually from water contaminated with faeces | Rice-water stools
53
Describe the microorganism cholera
Gram negative bacillus
54
Is cholera toxin mediated?
Yes
55
Enteric fever key points
Fever, headache, abdominal discomfort SE Asia or Indian subcontinant Isolate patient immediately
56
What are the two microorganisms that could be causing enteric fever and which is less severe?
``` Salmonella typhoid Salmonella paratyphoid (less severe) ```
57
Enteric fever clinical findings?
Abdominal tenderness | Hepatosplenomegaly
58
How is enteric fever diagnosed?
Blood culture
59
What antibiotic is given for enteric fever if stable, unstable (septic) or from an area of resistance?
Stable - ciprofloxacin Unstable - ceftriaxone Resistant - azithromycin
60
Amoebiasis key points
Protozoa Poor sanitation May cause abscess
61
In abscess caused by amoebiasis, what are the physical signs?
Dark patch in liver and abdominal discomfort | Point of tenderness over right lover ribs
62
What are the investigations for amoebiasis?
``` Stool microscopy CT to see abscess AXR to check for toxic mega-colon CXR - raised right semi-diaphragm May need endoscopy or biopsy ```
63
What is the management for amoebiasis?
Metronidazole | Paramomycin to clear the gut lumen of parasites
64
Giardiasis key points
Protozoa Faecal-oral spread Watery, malodorous diarrhoea, bloating and flatulance
65
Symptoms of giardiasis
Watery, malodorous diarrhoea Bloating and flatulence Abdominal cramps Weight loss
66
Investigation for giardiasis
Stool microscopy for cysts | Stool PCR when available
67
Treatment for giardiasis
Metronidazole or tinidazole
68
What are helminth infections associated with?
Eosinophilia
69
How would you get schistosomiasis?
Swimming in Lake Malawi
70
How would you get a tapeworm?
Undercooked meat