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Flashcards in Gastroenteritis Deck (19):
1

Norovirus

single stranded RNA virus
GII-4 strain
Seasonal - peaks in winter
Highly infectious
projectile vomiting, diarrhoea, abdominal cramping
immunity only lasts 6-14 weeks, no vaccination

2

Rotavirus

double stranded RNA virus
GI Strain
most common cause in children
stable in environment and resistant to hand washing
watery diarrhoea, abdominal pain, vomiting
no immunity, but subsequent infections less severe

3

COMPLICATIONS (4)

electrolyte disturbance
profound dehydration
chronic diarrhoea
metabolic acidosis

4

Adenovirus

double stranded DNA virus!!!
serotypes 40 and 41 cause gastroenteritis

5

Astrovirus

single stranded RNA virus
less severe cases, sporadic outbreaks

6

BARRIERS TO GI INFECTION (4)

Lysozyme
Stomach acidity
Small: epithelial cell turnover, mucous, secretory IgA, lymphoid tissue, bile
Large: epithelial turnover and normal flora

7

GI FLORA (4)

Bacteroides
Enterococci
E.coli
Klebsiella

8

Campylobacter

Gram neg bacilli
Foodborne esp poultry
ULCERATION, inflammation and bleeding
(no vomiting)
Bloody diarrhoea and fever
Can cause bacteraemia
Rarely post infectious demyelination (gullian barre)

9

Salmonella

Gram neg bacilli (salmonella enterica)
Poultry pork dairy
Multiplies in food
Watery diarrhoea, vomiting, fever (invasive)
Metastatic foci of infection
Bacteraemia

10

Shigella

Gram neg, s.sonnei (mild), s.dysenteriae (severe)
Mainly in children, faceo-oral
colonisation of terminal ileum
Produces shiga toxin (exotoxin) which damages epithelium -> can target glomerular endo -> HUS
Causes BLOODY diarrhoea and fever

11

Cholera

Vibrio cholerae
Based on O antigens = 01 and 0139
Can only live in fresh water - spreads through contaminated water
Potent exotoxin causes HIGH VOL diarrhoea
Profound dehydration, hypokalaemia, metabolic acidosis, hypovolaemic shock
Prompt oral or IV rehydration

12

Enterohaemorrhagic e.coli (EHEC)

includes e.coli 0157
large animal reservoirs (cattle and sheep)
attaching and effacing lesion, produces shiga like toxins
Bloody diarrhoea with pain and vomiting
no fever
haemolytic uraemic syndrome:
- haemolytic anaemia
- thrombocytopenia
- AKI

13

Staph aureus

gram positive cocci
intoxication: grows in foods and is ingested
produces heat stable enterotoxins
causes profuse vomiting and abdominal cramps
NO DIARRHOEA OR FEVER

14

Bacillus cereus

aerobic, spore forming gram positive bacilli
asoc with fried rice
spores survive boiling, on cooling they germinate and multiply
they can then survive frying
can cause emetic disease or diarrhoeal disease
(emetic has diarrhoea, diarrhoea no emetic)

15

Clostridium perfingens

gram positive bacilli
spores found in soil and animal gut
spores survive cooking and multiply in cooling food
food inadaquately re-heated to destroy organisms
produce enterotoxin in large intestine
causes watery diarrhoea NO VOMITING/FEVER

16

Clostridium botulinum

rare in UK
produces powerful, heat stable neurotoxin
enter peripheral nerves where they cause neuromuscular blockade at the synapses (block Ach) -> botulism
DESCENDING paralysis

wound botulism can occur in IVDU

17

C.difficile

spore forming gram positive
infection requires disruption of normal colonic flora
increased risk if PPI and laxative use
Pseudomembranous colitis -> colonic dilatation and perforation
Oral metronidazole then vancomycin

18

Listeria

gram positive coccobacilli
at risk: pregnant women, elderly and immunocompromised
asoc with unpasturised foods and soft cheese
invasive infection from GIT results in systemic spread via bloodstream -> septicaemia and meningitis

treat with IV ampicillin and gentamicin

19

H.pylori

gram neg, spiral shaped bacteria
diagnosed by faecal antigen or breath test
humans are the only reservoir
asymptomatic unless peptic ulcer develops (mostly duodenal)
can increase gastric cancer risk

treat with amoxicillin and clarithromycin