Harvest surface
Cotton swabs used to sample surfaces were vortexed in 50 mL falcon tubes filled with 10% phosphate buffer for one minute. Surface (swab) samples were concentrated onto 0.22 m membranes by filtering 30 mL for swab samples using a vacuum pump. The captured material on the filter was used to extract DNA from the swabs by using the PowerWater DNA Isolation Kit (Qiagen, MD, USA).