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. Acute sinusitis is most often caused by the common cold, which is a viral infection. In some cases, a bacterial infection develops. Risk factors. You may be at increased risk of getting sinusitis if you have: Hay fever or another allergic condition that affects your sinuses