Question:medium
A child with fever, red blood cells (RBCs) and pus in the stool. The causative organism is?
A child with fever, red blood cells (RBCs) and pus in the stool. The causative organism is?
Show Hint
Blood and pus in stool means an invasive, Shiga-toxin producing strain.
Updated On: Jun 24, 2026
- ETEC (Enterotoxigenic E. coli)
- EHEC (Enterohaemorrhagic E. coli)
- EPEC (Enteropathogenic E. coli)
- EAEC (Enteroaggregative E. coli)
Show Solution
The Correct Option is B
Solution and Explanation
Step 1: The combination of fever plus erythrocytes and leucocytes (pus) in the faeces is the hallmark of an inflammatory, dysentery-like diarrhoea, in contrast to a clear watery purge. The task is to match this with the correct E. coli strain.
Step 2: Enterohaemorrhagic E. coli elaborates Shiga (verocyto) toxin that injures the lining of the large bowel, producing grossly bloody stools containing inflammatory cells; it is also linked to haemolytic uraemic syndrome. Of the four choices it best fits a blood-and-pus stool.
Step 3: Eliminating the alternatives: the enterotoxigenic type yields a cholera-like watery output, the enteropathogenic type causes infantile watery diarrhoea through pedestal-forming adhesion, and the enteroaggregative type leads to prolonged watery diarrhoea with a stacked-brick adherence pattern. None routinely produces visible blood and pus.
Step 4: The answer is the enterohaemorrhagic strain.
\[\boxed{\text{EHEC}}\]
Step 2: Enterohaemorrhagic E. coli elaborates Shiga (verocyto) toxin that injures the lining of the large bowel, producing grossly bloody stools containing inflammatory cells; it is also linked to haemolytic uraemic syndrome. Of the four choices it best fits a blood-and-pus stool.
Step 3: Eliminating the alternatives: the enterotoxigenic type yields a cholera-like watery output, the enteropathogenic type causes infantile watery diarrhoea through pedestal-forming adhesion, and the enteroaggregative type leads to prolonged watery diarrhoea with a stacked-brick adherence pattern. None routinely produces visible blood and pus.
Step 4: The answer is the enterohaemorrhagic strain.
\[\boxed{\text{EHEC}}\]
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