Paper I
Question
Name four different bacteria causing dysentery
Answer
Four bacteria causing dysentery (inflammatory/invasive diarrhoea with blood, mucus, and tenesmus):
- Shigella species (S. dysenteriae, S. flexneri, S. boydii, S. sonnei) — the classical cause of bacillary dysentery, invading colonic epithelium and, in the case of S. dysenteriae type 1, also producing Shiga toxin.
- Enteroinvasive Escherichia coli (EIEC) — closely resembles Shigella genetically and pathogenically, invading and destroying colonic epithelial cells.
- Enterohaemorrhagic Escherichia coli (EHEC), notably serotype O157:H7 — produces Shiga-like toxin causing haemorrhagic colitis (bloody diarrhoea).
- Campylobacter jejuni — a common cause of invasive, sometimes bloody diarrhoea, particularly from undercooked poultry.
(Other valid examples: Salmonella non-typhoidal species can cause an invasive/inflammatory diarrhoea with blood in some cases; Yersinia enterocolitica; note that Entamoeba histolytica, causing amoebic dysentery, is a protozoan parasite, not a bacterium.)