A sinus infection is an infection in the upper respiratory tract and can be triggered by a number of things. It is also called sinusitis. It is when germs get into the sinuses and causes inflammation.There are several symptoms to determine if someone has a sinus infection. Tenderness or pressure around the nose, eyes, cheeks and forehead usually indicates a sinus infection. Headaches can also accompany the symptoms, furthering the discomfort brought on by one of these infections. Determine if you have a cold. A cold is the most common cause of a sinus infection. Check to see if there is any allergens or pollutants anywhere you visit routinely; like work or home. These can trigger acute sinusitis. Get checked for any bacterial in your body that could lead to a sinus infection. Bacterias such as Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Staphylococcus aureus can be the cause of a sinus infection. Get tested for any disease that weakens the immune system;