To Arly Helm
Re:   metronidazole prescribing. Per your question:

        >At what age/weight would a physician prescribe Flagyl for a child?


        At present there are no  FDA approved pediatric indications that I
know of.  However,  The Harriet Lane  Handbook(Pediatric)  lists doses
varying from 15-35 mg/kg/24 hrs depending on the source of infection.

        Nelson's Pocket Book of Pediatric Antimicrobial Therapy lists a
dose of 15 mg/kg/24 hrs(dividied q 8 hrs) for 5 days for therapy of  giardiasis.

        So to answer your question,  although not FDA approved,  it is
commonly used in pediatric NICU's and PICU's at almost all ages.

Tom Hale