Acute sinusitis is caused by:
A. Mixed aerobic and anaerobic bacteria
B. Streptococcus pneumonia***
Acute sinusitis is usually precipitated by an earlier upper respiratory tract infection, generally of viral origin, mostly caused by rhinoviruses, 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, Haemophilusinfluenzae, and Moraxella catarrhalis. Until recently, Haemophilusinfluenzae was the most common bacterial agent to cause sinus.