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. If an odontogenic infection involves the maxillary sinus, odontogenic sinusitis (ODS) may ensue. Odontogenic sinusitis can often spread to other sinuses such as the ethmoid, frontal and (less frequently) sphenoid sinus, and even to the contralateral nasal cavity. In rare instances, these infections may involve the orbit, causing orbital cellulitis, which may in turn result in blindness, or determine central nervous system complications such as meningitis, subdural empyema, brain abscess and life-threatening cavernous sinus thrombosis. Infection of the eye socket is a rare complication of ethmoid sinusitis, which may result in the loss of sight and is accompanied by fever and severe illness. Another possible complication is the infection of the bones (osteomyelitis) of the forehead and other facial bones – Pott's puffy tumor. Voice can also get infected resulting in laryngitis. This can result in hoarseness, change in voice, pain in throat, pain while talking, inaudible voice, dry cough and fever. Causes Acute Acute sinusitis is usually precipitated by an earlier upper respiratory tract infection, generally of viral origin, mostly caused by rhinoviruses (with RVA and RVC giving more severe infection than RVB), coronaviruses, and influenza viruses, others caused by adenoviruses, human parainfluenza viruses, human respiratory syncytial virus, enteroviruses other than rhinoviruses, and metapneumovirus. If the infection is of bacterial origin, the most common three causative agents are Streptococcus pneumoniae (38%), Haemophilus influenzae (36%), and Moraxella catarrhalis (16%). Until recently, H. influenzae was the most common bacterial agent to cause sinus infections. However, introduction of the H. influenzae type B (Hib) vaccine has dramatically decreased these infections and now non-typable H. influenzae (NTHI) is predominantly seen in clinics. Other sinusitis-causing bacterial pathogens include S. aureus and other streptococci species, anaerobic bacteria and, less commonly, Gram-negative bacteria. Viral sinusitis typically lasts for 7 to 10 days. Acute episodes of sinusitis can also result from fungal invasion. These infections are typically seen in people with diabetes or other immune deficiencies (such as AIDS or transplant on immunosuppressive antirejection medications) and can be life-threatening. In type I diabetics, ketoacidosis can be associated with sinusitis