Hello, examination of the lesion as a whole is important to say clinically infected. The signs pointing towards infection being purulent discharge, necrotic slough, red inflammed margins. A yellowish slough may be seen even in non-infected cases post burn. Since it is a slough and not new skin, you need to remove it through proper cleaning viz with hydrogen peroxide washes in appropriate dilutions, and for healing of postburn wound, aseptic dressings are must. Do consult a surgeon, if you note no improvement with these for debridement of the slough/debris. Thanks Take care.