The diagnosis of these complications can be assisted by noting local tenderness and dull pain, and can be confirmed by CT and nuclear isotope scanning. The most common microbial causes are anaerobic bacteria and "S. aureus". Treatment includes performing surgical drainage and administration of antimicrobial therapy. Surgical debridement is rarely required after an extended course of parenteral antimicrobial therapy. Chronic sinus infections may lead to mouth breathing, which can result in mouth dryness and an increased risk of gingivitis. Decongestants may also cause mouth dryness.