How many times a day are you told "I need antibiotics I coughed up some yellow/green stuff" Neither the color nor the consistency of nasal secretions helps to predict whether there is a bacterial infection. One should only consider treating sinus infections with antibiotics if the patient has:
Purulent nasal drainage for more than 10 days
Or if symptoms less than 10 days and one or more of the following significant facial pain, facial/periorbital swelling, dental pain, or temperature greater than 39'C
Antibiotic of first choice is Amoxicillin for 10-14 days. [Also consider Bactrim, Augmentin or Cipro for recurrent sinus infections]