What Causes Infection In Leg After Getting Stitches On It?

My age is 23, height 5'2, weight 64, i met with an accident on 26th may which resulted approx 15 stitches in my right leg. My injury is approx 10 cm long and 1.5 cm deep. I am going for daily dressing in which doctors are using beta dine, savlon for cleaning the injury but due to road accident, infection started in my leg. On Thursday, all stitches are removed but Yesterday during dressing, it was found that some portion is not recovered and that deep area is same as before. Doctor is going to take stitches again on the injured area. i am worried for my leg. please provide your guidance... :(