Gastroenteritis Flashcards

1
Q

What are the features of clostridium botulinum and what is the treatment

A

Gram +ve anaerobe
Canned/vacuum packed foods: Honey (kids),
beans (students)
Ingestion of preformed toxin (inactivated by cooking)
Blocks Ach release from peripheral nerves →
Descending paralysis (differentiates from GBS)

Tx: antitoxin

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1
Q

What are the features of Clostridium perfringens infection

A

Gram +ve anaerobe
Normal flora of the colon, but not the small bowel where the enterotoxin acts
Reheated meats, 8-16hrs incubation
Watery diarrhoea + cramps, lasts 24hrs
Also causes gas-gangrene

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2
Q

What are the features of Clostridium difficile infection and what is the treatment

A

Gram +ve anaerobe
2 exotoxins (A,B)
- Toxin A = enterotoxin = inflammation
- Toxin B = cytotoxin = virulence factor (more dangerous)
Pseudomembranous colitis
Suspect if severe diarrhoea + recent Hx of Abx (usually cephalosporins/fluorquinolones)

Tx: metronidazole, 2nd line vancomycin

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3
Q

What are the features of bacillus cereus infection

A

Gram positive rods, spore-forming
Reheated rice (spore germinates)– suspect after re-heated takeout
Short incubation ~4hrs
Sudden vomiting and watery, non-bloody diarrhoea
Superantigen — short incubation (4hrs)
Increased cAMP— long incubation (18hrs)
Self-limiting
May cause cerebral abscess

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4
Q

What are the features of staph aureus infection

A

Gram +ve clusters of cocci on gram stain, catalase, coagulase +ve, yellow colonies on blood agar
Spread by skin lesions on food handlers
Produces enterotoxin (acts as superantigen → IL1/2
release)
Short incubation ~2hrs
Prominent vomiting, watery non-bloody diarrhoea
Self-limiting

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5
Q

What are the features of E. Coli infection and how is it treated

A

Gram negative rod (Facultative anaerobes, glucose/lactose fermenters (LF), oxidase-negative)
Transmitted in faeces/contaminated water
ETEC: toxigenic, traveller’s diarrhoea
EIEC: invasive dysentery
EHEC: Haemorrhagic → HUS
HUS: Anaemia, thrombocytopenia, renal failure (0157:H7 toxin)
EPEC: Infantile diarrhoea (Paeds)

Tx: self-limiting, can treat with cipro

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6
Q

What are the features of typhoidal salmonella infection and how is it treated

A

Typhi + paratyphi
Multiplies in Peyer’s patches, spreads ERS
Enteric fever: Constipation, fever, rose spots,
splenomegaly

Tx: IV ceftriaxone → PO azithromycin

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7
Q

What are the features of non-typhoidal salmonella infection and how is it treated

A

Enteritides
Poultry, eggs, meat
Non-bloody diarrhoea, no fever

Tx: self-limiting, Ceftriaxone if required

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8
Q

What are the features of shigella infection and how is it treated

A

No animal reservoir (human → human transmission)
Affects the distal ileum + colon → mucosal inflammation, fever, pain, bloody diarrhoea (dysentery)

Tx: self-limiting, cipro if required

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9
Q

What are the features of vibrio infection

A

Cholera: Faeco-oral transmission (shellfish, oysters, shrimp). Rice water stool (massive diarrhoea without inflammation)
- Enterotoxin A and B subunit → persistent stimulation of adenylate cyclase

Parahaemolyticus: raw seafood (common in Japan)

Vulnificus: cellulitis in shellfish handlers

All self-limiting, treat dehydration, consider doxicyclin for para + vulni

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10
Q

What are the features of campylobacter jejuni infection and how is it treated

A

Undercooked poultry (chicken at a BBQ)
Prodrome of fever and headache, then abdo cramps and bloody diarrhoea
Lasts ~10d
Associated with GBS, reactive arthritis, Reiter’s

Tx: erythromycin or cipro in first 5 days

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11
Q

What are the features of listeria monocytogenes infection and how is it treated

A

Refrigerated food, unpasteurised dairy
Perinatal infection
Severe infection in immunocompromise
Water diarrhoea, cramps, headaches, fever

Tx: Ampicillin

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12
Q

What are the features of entaemoeba histolytica infection and how is it treated

A

Motile trophozoite in diarrhoea; Non-motile cyst in non-diarrhoeal illness
Flask-shaped ulcer on histology with 4 nuclei
Dysentery, flatulence, tenesmus
More common in MSM

Tx: metronidazole

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13
Q

What are the features of giardia lamblia infection and how is it treated

A

Pear-shaped trophozoite with 2 nuclei, 4 flagella and suction disc
Causes malabsorption of fat → foul-smelling non-bloody diarrhoea

Tx: metronidazole

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14
Q

What are the features of cryptosporidium parvum infection and how is it treated

A

Severe diarrhoea in immunocompromised
Infects jejunum
Oocysts seen in stool by modified Kinyoun acid fast stain

Tx: paromomycin

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15
Q

What are the features of viral causes of GI infection

A

Norovirus: secretory diarrhoea in adult outbreaks, no long-term immunity, low ID load with environmental resilience
Adenovirus: secretory diarrhoea <2yo
Rotavirus: secretory diarrhoea <6yo, dsRNA “wheel like”, exposure 2x → lifelong immunity

All self-limiting

16
Q

Define gastroenteritis

A

rapid onset diarrhoeal illness, lasting <2 weeks with diarrhoea (loose or unformed stool) ≥3/day or ≥200g of stool which is either viral or bacterial in aetiology

17
Q

Define diarrhoea

A

loose or watery stool, ≥3 times in 24 hours

17
Q

What defines acute, persistent, and chronic diarrhoea

A

Acute <14 days (may be viral or bacterial)
Persistent 14-29 days
Chronic >30 days (may be due to parasites and non-infectious aetiology)

18
Q

What are the differences between small and large bowel diarrhoea

A

Small bowel diarrhoea = watery, crampy abdominal pain, bloating and gas; inflammatory cells rare

Large bowel diarrhoea = small volume, painful, occur with blood/mucous; inflammatory cells common

19
Q

What investigations should be done for GI infections

A

Stool culture and sensitivity + for ova and parasites

U&Es
Glucose
Blood cultures

20
Q

Which causes of gastroenteritis are notifiable disease

A

Food poisoning: suspected
- Bacillus cereus
- Campylobacter spp.
- Clostridium perfringens
- Cryptosporidium spp.
- Entamoeba histolytica
- verocytotoxigenic Escherichia coli [including E. coli O157:H7]
- Salmonella spp.
- Giardia lamblia
- Yersinia pestis)
Haemolytic uraemic syndrome.
Infectious bloody diarrhoea, such as Shigella spp.
Enteric fever (typhoid or paratyphoid fever).
Cholera

21
Q

What necessitates hospital admission in gastroenteritis

A

Systemically unwell and/or there are clinical features suggesting severe dehydration and/or progression to shock
There is intractable or bilious vomiting or high-output diarrhoea
Acute-onset painful, bloody diarrhoea
Confirmed STEC infection O157
Suspected serious complication e.g. HUS, sepsis
Inadequate response to ORS

22
Q

Management for gastroenteritis:

A

Advice:
- Patient.info leaflets / NHS lefalets
- Regular fluid intake + fruit juice supplements
- Small, light, non-fatty, non-spicy meals may be better tolerated
- Prevent transmission: wash hands, always flush, clean bathroom at least once daily, do not share towels, washed all soiled clothing/linen separately
- EXCLUSION for at least 48 hours after the last episode of diarrhoea or vomiting

Medical
- Oral rehydration salt (ORS) solution
- 200-400mL after every loose motion
Given if: At an increased risk of dehydration e.g. elderly, immunocompromised, co-morbid conditions or concurrent illness OR Clinical features of dehydration but do not require admission

Mild-moderate diarrhoea → antidiarrhoeal drugs (NOT for bloody diarrhoea)

+ notify local health protection team