In nested PCR not sharp bands

[poonam sharma]

i'm doing nested PCR of microscopically positive stool samples. but after primary PCR there are no visible bands on gel and in nested pcr bands which r there r light. further i have to for restriction digestion then how can proceed with these light bands or what should i do for increasing the sharpness of my bands.

[danfive]

You either need more DNA template at beginning of PCR, more cycles --or DNA cleanup before PCR; stool can have PCR inhibitors, easy fix is running samples through a Chromaspin column.