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Year 3: Block 1: Infection > Infectious diarrhoea > Flashcards

Infectious diarrhoea Flashcards

1
Q

What is gastro-enteritis?

accompanying features?

A

three or more loose stools/day

fever, vomiting, blood or mucus in stool, abdominal pain

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2
Q

What is dysentery?

A

large bowel inflammation, bloody stools

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3
Q

Epidemiology of gastro-enteritis

A

food poisoning organisms
poor storage procedure
travel related infections (salmonella)
person to person spread - norovirus

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4
Q

most common cause of intestinal disorders?

A

viruses - campylobacter

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5
Q

What pathogen causes the most hospital admissions for intestinal disturbances?

A

salmonella

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6
Q

Campylobacter is the most common ?

A

foodborne pathogen

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7
Q

Defences against enteric infection?

A

HYGEINE
stomach acidity - antacids and infection
normal gut flora - c.diff diarrhoea
immunity - HIV, salmonella

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8
Q

those on antacids?

A

no protection rom normal gastric acid, more at risk

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9
Q

Clinical features of diarrhoeal illness? (3) - give examples

A

Non-inflammatory/secretory - CHOLERA
Inflammatory.- SHIGELLA DYSENTRY
Mixed picture - TOXINS - c.diff

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10
Q

Features of Non-inflammatory diarrhoea?

A

frequent watery stools and little abdo pain, secretory toxin-mediated

  • cholera - increases cAMP levels and Cl secretion
    enterotoxigenic E. coli (travellers’ diarrhoea)
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11
Q

Non-inflammatory diarrhoea treatment ?

A

rehydration

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12
Q

Mechanism of diarrhoea in cholera?

A

Increased cAMP results
in loss of Cl from cells
along with Na and K

Osmotic effect leads to
massive loss of water from
the gut

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13
Q

Features of inflammatory diarrhoeal illness?

treatment?

A

frequent fluid stools, pain, fever
bacterial infection, amoebic dysentery

antimicrobials, rehydration

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14
Q

Assessing the patient

A

history - Symptoms and their duration
risk of food poisoning - travel history
asses hydration - postural BP, skin turgor, pulse
features of inflammation (SIRS) - FEVER , raised WBC

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15
Q

Assessing an infant?

A 
sunken eyes and cheeks
decreased skin turgor
sunken fontelle
few or no tears
dry mouth or tongue
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16
Q

Fluid and electrolyte losses - when can this be severe?

what can you get? (2)

A

secretory diarrhoea

  • Hyponatraemia due to sodium loss with fluid replacement by hypotonic solutions
  • Hypokalaemia due to K loss in stool (40-80mmol/l of K in stools)
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17
Q

Assessing the patient - investigations

A
  • stool culture +/- molecular or Ag testing
  • blood culture
  • renal function
  • blood count - neutrophilia , haemolysis
  • abdo x-ray
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18
Q

Differential diagnosis of gastroenteritis? (3)

A

Inflammatory bowel disease
Spurious diarrhoea -secondary to constipation
Carcinoma

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19
Q

Diarrhoea and fever can occur with ?

A

sepsis outside the gut

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20
Q

Treatment of gastro-enteritis?

A

rehydration - iv or oral (community)

  • Oral rehydration with salt/sugar solution
  • iv saline
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21
Q

Campylobacter gastroenteritis features ? (3-4)

A
  • can have longer incubation > 7 days
  • Stools negative within 6 weeks
  • abdominal pain can be severe
  • uncommon to be invasive
  • Post-infection sequelae - Guillain-Barre syndrome, Reactive arthritis
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22
Q

Salmonella gastroenteritis features?

A
  • symptom onset usually <48 hrs after exposure
  • diarrhoea usually lasts <10 days
  • <5% positive blood cultures

abscesses other places in body, Osteomyelitis
post infection - IB is common

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23
Q

Prolonged Salmonella gastroenteritis may be associated with?

A

gallstones

24
Q

Routine Bacterial CultureCampylobacter - species that cause most infections?
isolated or outbreaks?

A

Two species cause most infections:
C. jejuni (90%)
C. coli (9%)

isolated

25
Q

Routine Bacterial CultureSalmonella - the 2 species?

A

S.enterica and S.bongori

26
Q

Most Common Salmonella Infections in UK?

A

Salmonella enteritidis and Salmonella typhimurium

often from abroad

27
Q

What do – S. typhi and S. paratyphi cause?

A

enteric fever (typhoid and paratyphoid) and not gastro-enteritis

28
Q

E.coli is an?

A

Infection. e.g. contaminated meat or person-to-person spread (low incoulum)

29
Q

E.coli is characterised by

A

frequent bloody stools
fever
seizures
lethargy

30
Q

What does E.coli O157 produce?

A

SHIGA TOXIN (same toxin also produced by Shigella spp) (previously called verocyto- toxin)

31
Q

Difference between E.coli and the toxin?

A

E.coli stays in gut, toxin gets into the blood

32
Q

When the E.coli toxin gets into the blood, what can happen?

A

hemolytic-uraemic (HUS) syndrome (haemolytic anaemia and renal failure)

33
Q

What is hemolytic-uraemic (HUS) syndrome characterised by?

A

renal failure, haemolytic anaemia and thrombocytopenia.

34
Q

E.coli patients need?

A

renal support

35
Q

E.coli treatment - avoid ?

A

antibiotics

36
Q

Toxin stimulates platelet activation which causes?

A

micro-angiopathy

37
Q

What are the 4 species of Shigella

A

S. sonnei, S.flexneri, S.boydii, S. dysenteriae) – outbreaks of Shigella sonnei in children’s nurseries

38
Q

several other forms of E. coli cause diarrhoea - name some

A

enteroinvasive
enteropathogenic
enterotoxic (traveller’s diarrhoea

39
Q

Occasional causes of food poisoning outbreaks (3)

A 
Staph aureus (toxin)
Bacillus cereus (re-fried rice)
Clostridium perfringens (undercooked meat/cooked food left out - toxin accumulates in spore formation)
40
Q

When should I give antibiotics?
Campylobacterdrugs
salmonella drugs

A

main therapy - rehydration
- immunocompromised, positive blood cultures
severe sepsis or invasive infection
chronic illness e.g. malignancy

C = macrolines, clarithromycin 
S = ciprafloxin
41
Q

When are antibiotics not indicated?

A

healthy patient with non-invasive infection

42
Q

What does C.diff produce?

A

enterotoxin (A) and cytotoxin (B) (inflammatory)

43
Q

Treatment of C.diff

A 
metronidazole
oral vancomycin - remains in gut
Fidaxomicin (new and expensive)
Stool transplants
surgery may be required
44
Q

In C.diff - a patient will often give a history of?

A

previous antibiotic treatment – the “4 C antibiotics”

45
Q

C.diff ranges from

A

mild diarrhoea to severe colitis

46
Q

CDI – prevention (5)

A
  • Reduction in broad spectrum antibiotic prescribing
  • Avoid 4 Cs – cephalosporins, co-amoxiclav, clindamycin, ciprofloxacin
  • Antimicrobial Management Team (AMT) and local antibiotic policy
  • Isolate symptomatic patients
  • Wash hands between patients
47
Q

CDI - Management

What are severity markers? (4)

A

Stop precipitating antibiotic (if possible)
- oral metronidazole if no severity markers

WCC>15
raised temp >38.5
acute rising creatinine
suspicion of toxic megacolon/colitis

48
Q

Parasitology - request lab?

A

stools looked at under the microscope

parasites, cysts and ova please” or P, C and O

49
Q

Uk parasites -protozoa 1
what is it called? what 2 forms?
symptoms?
transmitted by?

Treat with?

A
  • Giardia duodenalis - cyst form - trophozoites
  • diarrhoea, gas, malabsorption, failure to thrive, watery diarrhoea
  • direct contact with cattle/cats/dogs/other people
    food/water contaminated with faeces

with metronidazole

50
Q

Trophozoites can be seen on

A

or string test

51
Q

UK parasites - protozoa 2
symptoms?
exists in what 2 forms?
treatment?

A

Cryptosporidium parvum

cryptosoridosis - watery Diarrhoea, nausea and vomiting, abdo pain

oocysts , trophozoites

rehydration

52
Q

Imported parasites - Entamoeba histolytica causes?
long term complication?
treatment?

would do antibody detection for?

A 
amoebic dysentery (instestinal amoebiasis)
cyst and trophozoite forms

amoebic liver abscess - when aspirated - brown colour, anchovy pus

metronidazole
to remove cysts- further treatment

  • invasive disease
53
Q

Viral Diarrhoea: Rotavirus, Norovirus, Adenovirus

A

Rotavirus - most common in children under 5 - vaccine at 8 and 12 weeks

54
Q

What strains of adenovirus cause diarrhoea?

A

40 and 41

55
Q

Viral Diarrhoea: Norovirus is also known as

type of virus?

A

Winter vomiting disease – diarrhoea and vomiting

  • small round structured viruses (SRSV)
56
Q

Diagnosis of Norovirus?

A

PCR

very infectious -18 virus particles (1g stool=5 billion infectious doses

Year 3: Block 1: Infection (14 decks)

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