Page 156 - Medicine and Surgery

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152 Chapter 4: Gastrointestinal system

Investigations Investigations
Serodiagnosis is by fluorescent antibody titre, positivity Blood cultures are positive in 80% in week one and in
is low in asymptomatic carriers. Stool examination may 30% by week three. Stool cultures are more helpful in
revealthetrophozoites.Liverdiseaseshouldbesuspected the second to fourth weeks.
if alkaline phosphatase rises, hepatic ultrasound is used Serological testing is by the Widal test measuring
to confirm the diagnosis. serum agglutinins against O and H antigens.

Management Management
Metronidazole is the drug of choice, large liver abscesses Ciprofloxacin, chloramphenicol and amoxycillin have
require ultrasound guided percutaneous drainage. Pre- all been used.
vention is difficult due to the high prevalence of asymp- Supportivemanagementincludesfluidandelectrolyte
tomatic carriers, boiling water for 10 minutes kills the balance and management of complications.
cysts. Carrier state eradication is by 4 weeks of ciprofloxacin
and if unsuccessful cholecystectomy can be tried, as
the gallbladder is often the site of infection.
Enteric fever (typhoid and
Avaccine is available which gives some protection for
paratyphoid)
up to 3 years.
Definition
Typhoid (Salmonella typhi) and paratyphoid (Salmon- Botulism
ella paratyphi A, B or C)produce a clinically identical
disease. Definition
Botulism is a serious food poisoning caused by the Gram
Aetiology/pathophysiology positive bacillus Clostridium botulinum.
Humans are the only reservoir. Transmission is by the
faeco–oral route or via contaminated food and water. Aetiology
The incubation period is 10–14 days. Organisms pass The bacteria are soil borne, spores are heat resistant to
via the ileum and the lymphatic system to the systemic 100˚C. The most likely foods contaminated are canned
circulation causing a bacteraemia. Gut re-invasion leads and preserved. Three patterns are recognised:
to the clinical picture. Some secrete salmonella for over a 1 Food borne botulism in which toxin in the food is
year and measurement of Vi agglutinin is used to detect ingested.
carrier states. 2 Infant botulism in which the organism is ingested and
the toxin produced.
Clinical features 3 Wound botulism in which the organism is implanted
1 The condition typically runs a course of around 1 into a wound.
month. Week 1 results from the bacteraemia. There
is gradual onset of a viral like illness with headache Pathophysiology
and fever worsening over 3–4 days. There is initially Toxins are transported via the blood stream to the pe-
constipation. ripheral nerve synapses. Botulinum toxin acts to block
2 Week 2 the patient appears toxic with dehydration, neurotransmission.
constantfever,abdominalpainanddiarrhoea.Patients
develop an erythematous maculopapular-blanching Clinical features
rash with splenomegaly. The illness starts with nausea and vomiting 12–72 hours
3 During week 3 complications include pneumonia, afteringestingtheorganism.Neurologicalfeaturesresult
haemolytic anaemia, meningitis, peripheral neuropa- from neuromuscular blockade: blurred vision, squint
thy, acute cholecystitis, osteomyelitis, intestinal perfo- due to lateral rectus muscle weakness, the pupil is fixed
ration and haemorrhage. and unresponsive to light or accommodation. Laryngeal
4 Over the subsequent week there is a gradual return to and pharyngeal paralysis heralds the onset of a gener-
normal health. alised paralysis and respiratory insufficiency may result.