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GI infections Flashcards

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1
Q

What are the 3 types of GI infection?

A
  1. Secretory diarrhoea = Bowel changes + no fever (Cholera)
  2. Inflammatory diarrhoea = Bowel changes + fever (Campylobacter, Shigella)
  3. Enteric fever = Mainly severe fever (Salmonella typhi)
  • Secretory not inflammatory so doesn’t produce fever - doesn’t invade the mucosa (e.g. cholera binds to Cl- channel)
  • Inflammatory / enteric are inflammatory - invade mucosa, produce cytokines etc.
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2
Q

Catalase positive

A

S aureus

vs. Strep - catalase negative

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3
Q

Heat-labile pre-formed toxin
Food preparers spread (1/3 of population carry)
Secretory diarrhoea within 4h, resolves in 24h
TSST-1 superantigen = toxic-shock
Self-limiting

A

S aureus

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4
Q

Heat stable + heat-labile toxins
Rice water stool
Reheated rice
Spores

A

Bacillus cereus

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5
Q

3 types of clostridium

A

Botulinum
Perfringens
Difficile

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6
Q 
Botulism
Honey, canned + vacuum-packed products
Pre-formed toxin blocks ACh release
Dry mouth + visual disturbance then bilateral descending paralysis + death
Treat with antitoxin
A

Clostridium botulinum

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7
Q

Pre-heated foods (curry from hot plate)

Gas gangrene

A

Clostridium perfringens

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8
Q

Pseudomembranous colitis (post-Abx diarrhoea)
Following Abxs (3Cs - cephalosporins, cipro, clinda)
Gram positive anaerobic rod
Spreads really easily due to profuse diarrhoea

A

Clostridium difficile

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9
Q

What is the mechanism of pseudomembranous colitis?

A

Occurs following Abx use pt. 3Cs (cephalosporins, cipro, clinda)
Imbalance in normal gut flora
Clostridium difficile
Acute onset watery diarrhoea 4-9 days post-Abx
Exudative material creates ‘pseudomembrane’

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10
Q

What is the treatment for pseudomembranous colitis?

A

Oral metronidazole for 10-14d (sits in bowel)

If fails vancomycin

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11
Q 
Aesculin positive
B-haemolytic
Tumbling motility 'tumbleweed'
Unpasteurised dairy
Ampicillin treatment
A

Listeria monocytogenes

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12
Q

What are the 5 main enterobacteriae infections?

A
  • ETEC
  • EIEC
  • EHEC
  • HUS
  • EPEC
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13
Q

What can enterobacteriae infections be treated with?

A

Ciprofloxacin

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14
Q 
Enterobacteriae
Gram and oxidase negative
Facultative anaerobe
Traveller
Heat labile (stim adenyl cyclase, cAMP), heat stable (stim GC)
A

E coli (ETEC)

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15
Q

(Enterobacteriae
Gram and oxidase negative
Facultative anaerobe)
Dysentery, like shigella

A

E coli (EIEC)

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16
Q

(Enterobacteriae
Gram and oxidase negative
Facultative anaerobe)
Haemorrhagic

A

E coli (EHEC)

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17
Q

(Enterobacteriae
Gram and oxidase negative
Facultative anaerobe)
Paediatric diarrhoea in newborn nurseries

Study These Flashcards
A

E coli (EPEC)

18
Q 
(Enterobacteriae
Gram and oxidase negative
Facultative anaerobe)
Swimming in open water, petting zoos
0157-H7 toxin
MAHA, thrombocytopenia, renal failure
19
Q 
Non-lactose fermenters
H2S black colonies
TSI agar
Selenite F broth
3 toxins - O, H, Vi
20
Q

What are the 3 types of salmonella toxin?

Study These Flashcards
A

O - cell wall
H - flagellar
Vi - capsular

21
Q

What are the 2 main salmonella?

Study These Flashcards
A

Enterides

Typhi (enteric fever)

22
Q 
Multiplies in Peyer's patches
Rose spots
Slow onset fever + constipation
Relative bradycardia
Ceftriaxone
Study These Flashcards
A

Salmonella typhi (enteric fever)

23
Q

Poultry eggs and meat e.g. BBQ
Non-bloody diarrhoea
Usually self-limiting

Study These Flashcards
A

Salmonella enterides

24
Q 
Non-motile
H2S producers
Shiga enterotoxin
Distal ileum + colon
Bloody diarrhoea
Sonnei, dysenteriae, flexneri (MSM)
25
``` Curved comma-shaped oxidase positive Rice water stool Shellfish, oysters, shrimp Enterotoxin with A + B sub-units Rehydration therapy Supportive ```
Vibrio cholera
26
How does cholera cause rice water stool?
Enterotoxin has A (active) and B (binding) sub-units B binds to GM1 on epithelial cells A activates cAMP intracellularly - active secretion of chloride and sodium ions - osmotic pull of water
27
Curved comma-shaped oxidase positive Eating raw or undercooked seafood in Japan Doxycycline
Vibrio parahaemolyticus
28
Curved comma-shaped oxidase positive Shellfish handler scratched by coral Cellulitis then fatal septicaemia with D+V Doxycycline
Vibrio vulnificus
29
Curved S shaped oxidase positive Microaerophilic, mobile Get Guillain-Barre, reactive arthritis (Reiter's) after diarrhoea Unpasteurised milk, poultry (chickens pecking milk bottles) Super bad bloody foul smelling diarrhoea (Can treat erythro or cipro but symptoms usually gone by the time results get back)
Campylobacter jejuni
30
S-shaped vs. comma-shaped
S-shaped - campylobacter | comma-shaped - vibrio (cholera)
31
Peyer patch invasion - mesenteric LN enlargement - then invades Necrotising granulomas 3Ps - pericarditis, peritonitis, pharyngitis Cold enrichment
Yersinia enterocolitica
32
Immunosuppressed | Sub-Saharan Africa
TB
33
Food, water, soil MSM Motile trophozoite in diarrhoea / non-motile cyst if no diarrhoea Flask shaped ulcer Water filters, boiling water whilst camping RUQ pain from liver abscess
Entamoeba histolytica
34
Pear shaped trophozoite Fould smelling steatorrhoea containing cysts Excessive flatulence, bloating, explosive diarrhoea Mental hospitals, travellers
Giardia lamblia
35
``` Kinyoun acid fast stain - cysts Severe diarrhoea in young child Swimming pool parties or rivers in slums Jejenum Paromomycin Tx ```
Cryptosporidium parvum
36
Main protozoa in GI disease
Entamoeba histolytica Giardia Cryptosporidium
37
Main viral in GI disease
Norovirus Rotavirus Adenovirus
38
What bacterial vaccines are available?
Cholera Campylobacter ETEC Salmonella Typhi Only given if going to endemic area or high risk in terms of army / MSF volunteer for example
39
What viral vaccines are available?
Rotavirus
40
What bugs can metronidazole be used to treat?
(GET you difficult bugs) | Giardia, Entamoeba, Trichomonas, C difficile
41
Story to remember vancomycin action
Treats Gram positive Ambulance is 'Van' with big red cross on it Give IV as cannot pass through lining of intestine...but in C difficile give orally as just has to stay in gut so localises Side effect = Red Man Syndrome - driver of ambulance with red face (sudden erythematous pruritic rash on face / neck / torso)

Microbiology (19 decks)

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