Infectious Diarrhoea Flashcards
1
Q
Which are the good gut bugs?
A
Anaerobes:
- bacteria spp
- anaerobic strep
- clostridia
- bifidobacterium
Aerobes:
- e.coli
- lactobacillus
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
3
Q
Which are the bad gut bugs?
A
Bacterial
- C.diff
- Camp
- Salmonella
- Shigella
- E.coli
Viral
- Norovirus
- Rotavirus
Protozoal
- Giardia
- Cryptosporidium
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
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
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
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
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
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
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
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
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
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
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
15
Q
What are non specific markers of illness?
A
- WCC/CRP = ifnlam
- U+E’s = renal impairment/failure
- FBC = WCC + anaemia from malabsorption
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
