bacterial 16S rRNA gene (V3-V6):coronal sulcus swab
100 microliter of the swab eluent from each sample were lysed using pressure-cycling technology (Pressure Biosciences, South Easton, MA, USA), purified using Qiagen AllPrep DNA/RNA Mini Kit (Qiagen, Valencia, CA, USA), and eluted using 100 microliter of Buffer EB. Penile microbiota was characterized by sequencing the bacterial 16S rRNA gene (V3-V6) using the  qPCR V3F primer on GS FLX (454 Life Sciences, Branford, CT, USA)