Dysenteries can be caused by two main pathogens - bacillary and amoebic. Bacillary dysentery is caused by Shigella bacteria transmitted through contaminated food or water. It causes ulcerations in the colon and occasionally ileum. Amoebic dysentery is caused by Entamoeba histolytica transmitted through ingestion of cysts. It causes characteristic flask-shaped ulcers in the large intestine, especially the cecum, rectum, and flexures. Complications of both forms include hemorrhage, perforation, and liver abscesses.

1. Dysenteries
By Dr Utsav Parmar

2.  ‘Dysentery’ is used to mean diarrhoea
with
 abdominal cramps,
 tenesmus and
 passage of mucus in the stools, from
any cause
 2 main forms of dysenteries—
 bacillary and amoebic.

3. Bacillary Dysentery
 Infection by shigella species: S.
dysenteriae, S.flexneri, S. boydii and
S. sonnei
 Infection occurs by foeco-oral route
and is seen with poor personal
hygiene, in densely populated areas,
and with contaminated food and water
 common housefly plays a role in
spread of infection

4. Grossly
 The lesions are mainly found in the
colon and occasionally in the ileum.
 Superficial transverse ulcerations of
mucosa of the bowel wall occur in the
region of lymphoid follicles but
perforation is seldom seen.
 The intervening intact mucosa is
hyperaemic and oedematous.
 Following recovery from the acute attack,
complete healing usually takes place.

5. Microscopically
 mucosa overlying the lymphoid
follicles is necrosed.
 The surrounding mucosa shows
congestion, oedema and infiltration by
neutrophils and lymphocytes.
 The mucosa may be covered by
greyishyellow ‘pseudomembrane’
composed of fibrinosuppurative
exudate.

6. complications
 of bacillary dysentery are
 haemorrhage,
 perforation,
 stenosis,
 polyarthritis and
 iridocyclitis

7. AMOEBIC DYSENTERY
 infection by
 Entamoeba histolytica
 more prevalent in the tropical
countries and primarily affects the
large intestine

8.  Infection occurs from ingestion of cyst
form of the parasite.
 The cyst wall is dissolved in the small
intestine from where the liberated
amoebae pass into the large intestine.
 Here, they invade the epithelium of the
mucosa, reach the submucosa
 produce the characteristic flask-
shaped ulcers.

9. Grossly
 early intestinal lesions appear as
small areas of elevation on the
mucosal surface.
 In advanced cases, typical flask-
shaped ulcers having narrow neck and
broad
base are seen.
 They are more conspicuous in the
caecum, rectum and in the flexures

10. Microscopically
 the ulcerated area shows chronic
inflammatory reaction consisting of
lymphocytes, plasma cells, macrophages
and eosinophils.
 The trophozoites of Entamoeba are seen in
the inflammatory exudate and are
concentrated at the advancing margin of
the lesion.
 Intestinal amoebae characteristically have
ingested red cells in their cytoplasm.
 Oedema and vascular congestion are
present in the area surrounding the ulcers

12. Complications
 of intestinal amoebic ulcers are:
 Amoebic liver abscess or
 amoebic hepatitis,
 perforation,
 haemorrhage
 formation of amoeboma which is a
tumour-like mass