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150 Chapter 4: Gastrointestinal system

Investigations Clinical: Patients suffer from bloody diarrhoea and
Diagnosis is made on stool culture. Sigmoidoscopy if colitis. Haemolytic uraemic syndrome may com-
performed reveals an inflamed mucosa with ulceration plicate infections with EHIC.
similar to that seen in inflammatory bowel disease. 5 Enteroaggregative E. coli (EAEC or EaggEC).
Pathogenesis: The bacteria produce a cytotoxin

and stimulate IL-8 production. It is most com-
Management
mon in the developing world but also found in
Treatment is symptomatic. Severe cases may be treated
the United Kingdom, especially in immunocom-
with trimethoprim or ciprofloxacin. Outbreaks may oc-
promised hosts.
cur and require notification and source isolation.
Clinical: Traveller’s diarrhoea which lasts up to 4

days, or persistent diarrhoea in immunocompro-
Enteric Escherichia Coli infections mised.
Definition
Management
The E. coli that cause enteric diseases are of different Patients require adequate rehydration, normally orally.
serotypes from those that cause diseases elsewhere. Five Most infections are self-limiting. In severe cases, partic-
main types are recognised. ularly if there are systemic symptoms, ciprofloxacin is
used. It has been suggested from retrospective studies
Aetiology/pathophysiology that treatment of E. coli 0157 with antibiotics may result
1 Enterotoxogenic E. coli (ETEC) produces a diarrhoeal in increased rates of haemolytic uraemic syndrome, but
illness. the treated patients were also more seriously unwell.
Pathogenesis: Two toxins are produced, one that

is heat stable and one that is heat labile. The tox- Pseudomembranous colitis
ins are coded for on plasmids and can therefore be
Definition
transferred between bacteria. The heat labile toxin
Pseudomembranous colitis is a form of acute bowel in-
resembles cholera toxin and acts in a similar way.
flammation caused by A and B toxins of Clostridium
Theheatstabletoxinactivatesguanylatecyclasealso
difficile.
resulting in secretory diarrhoea.
Clinically three syndromes occur with this infec-

tion: A cholera-like illness, traveller’s diarrhoea and Aetiology/pathophysiology
Usually seen in association with the use of broad-
childhood diarrhoea, which may vary in severity.
2 Enteroinvasive E. coli (EIEC) produces a very similar spectrum antibiotics particularly clindamycin. Other
illness to bacilliary dysentery (shigellosis). implicated antibiotics include ampicillin, tetracycline,
3 Enteropathogenic E. coli (EPEC) causes an infantile cephalosporins. Antibiotics reduce the presence of nor-
gastroenteritis. mal protective bowel flora and allows Clostridium to
Pathogenesis:Toxinsarethoughttobeinvolved,the
multiply, causing inflammation and necrosis of bowel
bacteria attaches to and damages intestinal epithe- mucosa.
lium.
Clinical: The condition causes a diarrhoeal illness
Clinical features
primarily in children below 2 years. Patients (often already hospitalised) develop diarrhoea
4 EnterohaemorrhagicE.coli(EHIC)includesverotoxin with variable fever and abdominal cramps. The stools
producing E. coli 0157:H7. are green, foul smelling and may contain pseudomem-
Pathogenesis: The bacteria produce a shigella-like
branes, fragments of mucosal slough.
cytotoxin (Shiga toxin). Infections are associated
with contaminated food, particularly hamburgers, Investigations
only a small bacterial load is required to cause dis- At sigmoidoscopy the mucosa is erythematous, ulcer-
ease. ated and covered by a membrane-like material.