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Usually it is not pus cells but bacteria, that is detected in stool examination under microscope. Some of the bacteria are normally seen in the stool and are not of any consequence, such as E. Coli.
There are certain other bacteria which cause diarrhoea
. These need to be identified, culture and sensitivity test done to determine which antibiotic will be best suitable to eradicate that infection.
Wishing your child all the best.