Infective diarrhoea

Question 1

e.coli

Answer 1

Escherichia coli Common amongst travellers
Watery stools
Abdominal cramps and nausea

Question 2

Giardiasis

Answer 2

Giardiasis is caused by the flagellate protozoan Giardia lamblia. It is spread by the faeco-oral route.

Risk factors
foreign travel
swimming/drinking water from a river or lake
male-male sexual contact

Features
often asymptomatic
non-bloody diarrhoea
steatorrhoea
bloating, abdominal pain
lethargy
flatulence
weight loss
malabsorption and lactose intolerance can occur

Investigations
stool microscopy for trophozoite and cysts: sensitivity of around 65%
stool antigen detection assay: greater sensitivity and faster turn-around time than conventional stool microscopy methods
PCR assays are also being developed

Treatment is with metronidazole.

Question 3

cholera

Answer 3

Overview
caused by Vibro cholerae - Gram negative bacteria

Features
profuse ‘rice water’ diarrhoea
dehydration
hypoglycaemia

Management
oral rehydration therapy
antibiotics: doxycycline, ciprofloxacin

Question 4

Bacilleus cereus

Answer 4

Bacillus cereus –short incubation

. Under-cooked or reheated rice is most classically associated with B. cereus .

B. cereus causes two distinct food poisoning syndromes:
An emetic syndrome resulting from ingestion of the heat-stable toxin cereulide. Disease can occur from toxin ingestion even if the bacteria are killed during cooking. Symptoms typically occur between 0.5 and 6 hours of ingestion. Diarrhoea symptoms may also occur.

A diarrhoeal syndrome associated with separate exotoxins such as haemolysin BL. Patients typically complain of crampy abdominal pain and diarrhoea. Usual onset time 8-16 hours.
Symptoms typically resolve within 24 hours in both syndromes.

In immunosuppressed patients: bacteraemia, endocarditis, musculoskeletal and CNS infection may occur.

Treatment:
Treatment: rarely required for food poisoning syndrome. Most strains produce beta-lactamase and vancomycin is suggested as the empiric antibiotic of choice in some guidelines.

Question 5

Staph aureus

Answer 5

Staphylococcus aureus
Severe vomiting
Short incubation period -with baccilius

Question 6

shigella

Answer 6

Bloody diarrhoea
Vomiting and abdominal pain

Question 7

campylobacter

Answer 7

Campylobacter is the commonest bacterial cause of infectious intestinal disease in the UK. The majority of cases are caused by the Gram-negative bacillus Campylobacter jejuni. It is spread by the faecal-oral route and has an incubation period of 1-6 days.

Features
prodrome: headache malaise
diarrhoea: often bloody
abdominal pain: may mimic appendicitis

Management
usually self-limiting
the BNF advises treatment if severe or the patient is immunocompromised.
the first-line antibiotic is clarithromycin
ciprofloxacin is an alternative although the BNF

Complications
Guillain-Barre syndrome may follow Campylobacter jejuni infections
reactive arthritis

Question 8

Ameabosis

Answer 8

Amoebic dysentery
profuse, bloody diarrhoea
there may be a long incubation period
stool microscopy may show trophozoites if examined within 15 minutes or kept warm (known as a ‘hot stool’)
treatment
oral metronidazole
a ‘luminal agent’ (to eliminate intraluminal cysts) is recommended usually as well e.g. diloxanide furoate