GI Infections

Question 1

Norovirus

Answer 1

1 day incubation -> acute D+V lasting 2+ days, very infectious, spread by contact, food, notifiable disease
Dx = stool antigen

Question 2

Rotavirus

Answer 2

1-3d incubation -> watery diarrhoea + vomiting for up to 1 week (longer than norovirus) Dx: stool antigen
Live vaccine in childhood (2 doses, 12 weeks and 8 years)

Question 3

Campylobacter Jejuni

Answer 3

Incubation 2-5d -> dysentry + pain + headache
Complications: sepsis, hepatitis, pancreatitis, miscarriage, REACTIVE ARTHRITIS, GUILLIAN BARRE
Tx = clarithromycin or ciprofloxacin

Question 4

Salmonella

Answer 4

Non-typhoidal - incubation 6h-3d -> dysentry + cramps
Complications: Sepsis, meningitis, OSTEOMYELITIS + SEPTIC ARTHRITIS (sickle cell)
Tx = ciprofloxacin or clarithromycin

Question 5

Staph Aureus

Answer 5

Pre-formed toxins -> 30mins to 6 hrs -> sudden V+D, cramps

Question 6

Bacillus cereus

Answer 6

Spores reactivated by heat (reheating rice) -> 8h -16 h -> V+D, self limiting

Question 7

Listeria Monocytogenes

Answer 7

Variable incubation (up to months)
Vague, flu like symptoms -> diarrhoea in more immunocompromised
Complications: abscess, endocarditis, MENINGOENCEPHALITIS (extremes of age), pregnancy loss or preterm delivery (placentitis/aminoitis)
Tx: Amoxicillin

Question 8

E. coli

Answer 8

O157:H7 -> shigella toxin producing Ecoli (STEC) -> haemorrhagic colitis (dysentry).
Complications: 10% haemolytic uraemic syndrome. DONT GIVE ABX as increase risk of HUS.

Enterotoxigenic E Coli (ETEC) -> most common cause of travellers diarrhoea

Question 9

Shigella spp

Answer 9

1-2 days incubation -> dysentry, tenesmus
RF = MSM
Complications: REACTIVE ARTHRITIS, HUS, MEGACOLON (avoid anti-diarrhoea meds)

Question 10

Vibrio Chlorae

Answer 10

Incubation 2-5d -> rice water diarrhoea

Tx = electrolyte replacement

Question 11

Giardia

Answer 11

Incubation 1-3 weeks, persistent diarrhoea, flatulence, bloating, pain, malabsoptive symptoms
Sx last WEEKS TO MONTHS
Faeco-oral spread of cysts (lake water)
Dx: stool microscopy, >3 samples due to intermittent shedding
Cx: lactose intolerance
Tx: Metronidazole

Question 12

Cryptosporidium

Answer 12

Self limiting diarrhoea in immunocompetent (contaminated water)
SEVERE AND CHRONIC diarrhoea in immunocompromised (HIV)
No clear Tx

Question 13

Entamoeba Histolytica

Answer 13

Faecal oral spread (cysts destroyed by boiling), intestinal amoebiasis -> insidious/relapsing colitis, appendicitis, toxic megacolon
Invasive amoebiasis -> liver abscess: high swinging fevers, RUQ pain, LFT cholestatic picture
Dx: microscopy
Tx metronidazole