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.
Causes of sinusitis. Sinusitis is caused by too much mucus, or a swelling of the lining of the sinuses and nose, which can block the narrow channels. This can occur during a cold, or may be due to allergy (for example, hayfever) or irritation of the linings of the sinuses (for example, from chlorine in a swimming pool).