Infectious Diarrhoea Flashcards

1
Q

Which are the good gut bugs?

A

Anaerobes:

  • bacteria spp
  • anaerobic strep
  • clostridia
  • bifidobacterium

Aerobes:

  • e.coli
  • lactobacillus
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2
Q

What are the beneficial properties of intestinal bacteria?

A
  • Enterohepatic circulation - bacterial enzymes aid intestinal absorption
  • Nutrition - bacterial enzymes involved in metabolism of key vitamins e.g. B7, B12, K, folic acid
  • Infection - normal flora discourages exogenous infection + prevents overgrowth
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3
Q

Which are the bad gut bugs?

A

Bacterial

  • C.diff
  • Camp
  • Salmonella
  • Shigella
  • E.coli

Viral

  • Norovirus
  • Rotavirus

Protozoal

  • Giardia
  • Cryptosporidium
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4
Q

What is Clostridium difficile and how is it managed?

A
  • Gram +
  • Toxin mediated disease affecting large bowel - destruction of normal gut flora
  • Faecal-oral spread
  • Part of normal flora for children < 2
  • Elderly, hospitalised pt + those on antibiotics = > risk
  • Asymptomatic in some
  • WCC, renal function, temperature, evidence of colitis
  • Management = stop offending agents, anti c.diff antibiotics, surgery
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5
Q

What is Campylobacter and how is it managed?

A
  • Gram negative rod
  • Commonest bacterial cause of infectious intestinal disease in UK
  • Mostly due to C.jejuni (poultry/birds), some C.coli (pigs)
  • Via contaminated food
  • Low infective dose
  • Toxin mediated disease
  • IP 1-7 days
  • Symptoms 2-7 days
  • Post infection sequelae > reactive arthritis, gullian-barre syndrome
  • Management = usually self limiting and no need antibiotics, erthythromycin can shorted duration
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6
Q

What is Salmonella and how is it managed?

A
  • Gram negative rod
  • S.enteritidis = food poisoning
  • S.typhi + S.paratyphi = typhoid
  • Zoonoses
  • Poorly cooked/contaminated meat
  • Primarily affects SI
  • Bacteraemia can occur in immunocompromised
  • Non GI manifestations: osteomyelitis in sickle cell, focal infections, meningitis + otitis media in neonates
  • Usually no antibiotics
  • If v unwell + bacteraemic - quinolines, macrolides, cephalosporins
  • Typhoid/ paratyphoid (enteric fever) - potentially fatal, insidious onset stepwise fever, cough + constipation common > requires antibiotics - fluoroquinolones, ceftriaxone, azithromycin
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7
Q

What is E.coli and how is it managed?

A
  • Gram negative rod
  • ETEC - infantile diarrhoea in developing world, travellers, supportive treatment
  • EIEC - ciproflaxacin if severe
  • EPEC - NOT toxin mediated, ciproflaxacin if severe
  • VTEC
  • ileum + colon, infants + elderly
  • can cause HUS esp in < 5 = MIHA, renal failure, low platelets, CNS features, neutrophilia
  • management = early fluid resuscitation, cautious use antibiotics, withhold opiates/NSAIDS + anti-motility agents
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8
Q

What is Cholera and how is it managed?

A
  • Gram negative rod, motile
  • Faecally contaminated water + food
  • Profuse painless watery stool
  • Manage with aggressive rehydration
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9
Q

What is Shigella and how is it managed?

A
  • Gram negative
  • S.dysenteriae = most severe
  • Faecal oral
  • Manage by rehydration, a antibiotics if v ill
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10
Q

What is Norovirus and how is it managed?

A
  • RNA virus
  • Commonest cause of GI outbreaks in healthcare + cruise ships
  • Short IP 24-48hrs
  • Fever + GI symptoms (vomiting +/- diarrhoea)
  • Management = supportive
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11
Q

What is Rotavirus and how is it managed?

A
  • Commonest diarrhoeal cause in children requiring hospitalisation
  • Faecal-oral + contaminated enviro
  • Same management as norovirus
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12
Q

What is Giardia and how is it managed?

A
  • Intestinal protozoon
  • Cyst passed in stool > survives in enviro, highly infectious
  • Via contaminated water usually
  • Often asymptomatic
  • Diarrhoea = bulky, pale + offensive smelling
  • Abd bloating + anorexia + nausea
  • Chronic diarrhoea in some > malabsorption syndrome
  • Treated with Metronidazole, Tinidazole
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13
Q

What is Cryptosporidium and how is it managed?

A
  • Intestinal sporozoa
  • SI
  • Major cause diarrhoea in immunocompromised
  • Via contaminated water
  • Highly resistant to disinfectants
  • IP 2-14 days
  • Diarrhoea with abd pain + weight loss
  • In AIDS pt managed with HAART
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14
Q

What is Entamoeba histolytica and how is it managed?

A
  • Underdeveloped countries
  • Can cause colitis + liver abscesses
  • May require prolonged treatment with metronidazole + liminal amoebicide
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15
Q

What are non specific markers of illness?

A
  • WCC/CRP = ifnlam
  • U+E’s = renal impairment/failure
  • FBC = WCC + anaemia from malabsorption
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16
Q

Why may a biopsy be useful in C.diff?

A

To exclude IBD

17
Q

What may blood and pus in stool microscopy indicate?

A

Infective diarrhoea

18
Q

How do you detect C.diff in stool?

A

Screen with PCR + confirm with toxin

19
Q

How are non C.diff infections managed?

A
  • Oral rehydration in mild cases
  • May require IV fluid +/- electrolytes
  • Indications for antibiotics = invasive salmonella (esp. typhi strains), parasitic infections, early campylobacter
  • Do NOT give antibiotics for HUS causes by toxigenic E.coli