Since Pus cells are more than 5/HPF, and girls have a higher risk of UTI(Urinary Tract Infection), you need to get a URINE CULTURE, to confirm UTI .....
Next Steps
Send a sample for Urine Culture
Increase her water intake
If there are any associated symptoms like Fever/ Vomiting/Burning sensation while passing URINE, you may start Antibiotic, which has to be revised after getting the Urine Culture report