CHOLERA

Q. A 50-year-old man develops nonbloody watery diarrhea while working as an aid worker in a refugee camp in Bangladesh. He arrived in the area 2 days ago. A stool smear shows no WBCs.
He subsequently develops dehydration and electrolyte abnormalities leading to cardiac and renal failure. Which of the following organisms is the most likely cause of this man’s enterocolitis?
(A) Clostridium difficile
(B) Giardia lamblia
(C) Helicobacter pylori
(D) Salmonella species
(E) Vibrio cholerae

Ans: E.

Vibrio cholerae causes watery stools, often called rice-water stool.

This illness is not accompanied by abdominal pain, but the symptoms are due to dehydration leading to electrolyte imbalances.

 Cholera toxin causes uncontrolled stimulation of adenylate cyclase; the resulting excess of

  cAMP causes uncontrolled secretion of chloride and water (due to the osmotic gradient),

 resulting in extremely watery diarrhea accompanied by electrolyte imbalances.

 Clostridium difficile causes severe non bloody diarrhea associated with pseudomembranes

Diarrhea may be bloody when very severe mucosal ulceration occurs. C. diffi cile infection is associated with previous antibiotic treatment

 
Giardia lamblia is a protozoan parasite that is a frequent cause of nonbloody diarrhea.

 The stools are usually foul-smelling and contain fat (steatorrhea). It is  less severe than the diarrhea caused by Vibrio cholerae.

 Helicobacter pylori infection causes gastritis and would not cause the symptoms describe by the patient.

Salmonella species invade the mucosa to cause bloody diarrhea and can be acquired from poultye meat & eggs.