What signs and symptoms differentiate a bacterial vs a viral acute sinus infection?

Time. Almost all bacterial sinus infections occur following a viral upper respiratory infection. In the first several days following a cold the sinuses inflame due to the viral illness. About 15 to 20% of the time a viral illness becomes bacterial. 7 to 10 days after illness if symptoms persist or worsen with cough, headache, congestion, bacterial is now a likelyhood.