chemical formula a combination of symbols used to express the chemical components of a substance. empirical formula a chemical formula that expresses the proportions of the elements present in a substance.
The bacteria streptococcus pneumoniae is the most common cause of acute bacterial sinusitis. This type of bacteria can be resistant to the most common types of antibiotics at standard dosages, although there are other antibiotics that can be used to treat the condition.
Acute sinusitis is usually caused by a viral or bacterial infection. The common cold, which is caused by a virus, may lead to swelling of the sinuses, trapping air and mucus behind the narrowed sinus openings.