What Causes Strep On Penis?

It started with an odd itch on one side of my penis. Persisted for 2-3 days...itched only the odd time. I checked my penis,...where the itch was turned out to be reddish and seemed like I had a problem. This occurred in the beginning about 2 days after having sex. I self treated with a healing cream for a couple days which didn t help, so switched to aloe vera gel for a couple days. The problem was getting worse. Went to a clinic. Doc took a swab, and I had to get a prescription... (30) Fucidin H 2% & 1%. Fusidic Acid & HC Acetate,...a cream in a tube. That s what it says on the tube. Doc said try it for 30 days and if not better go see him again. I asked the Doc how I would get whatever it was I had . He answered her . Today, I get a call from some gal at the clinic that told me I had Light A Penis Strep and that it should clear up in a couple days...it has been getting better. Redness has lessened, as well as swelling and itch. I asked what it was caused from...she said she didn t know. My question is this : How would I get Strep on my penis ?? Thank You , Norm.