Thanks for consulting at Healthcare Magic. Bone or joint infection in children is most commonly caused due to organism called Staphylococcus aureus. This organism can be resistant to antibiotics that s why your daughter did not respond to initial course of antibiotics. Surgical removal of infected part and puss along with culture sensitivity will help in determining the antibiotic to which organism is sensitive. Intravenous antibiotics will be required. Investigations like MRI may be required to find out the exact extent of infection. Most children will completely recover from bone infections after proper treatment.