I have been isolating DNA from buccal brushes for quite some time and I have just recently started isolating from brushes that have been sent to us from patients through the mail. These new samples have a much higher DNA content then the fresh samples that we take and freeze within an hour. I am worried that the excess DNA is from bacteria that grew during shipment of the brushes through the mail. These brushes were not dried before mailing so the combination of moisture and cells taken from the mouth left at R/T for days leads me to believe there might have been some bacterial growth. Is there a way that I could check for this? The only thing I can think of is to run a gel and look for DNA degradation which might indicate bacterial growth. I looked at a couple samples under the microscope before lysing the cells and all I saw were epithelial cells.