Although I agree somewhat with Ursus take on dato, just want to assure most guys, if a women has cleaned well down there, I would put the activity no more hazardous than touching a pole on the subway during rush hour.
I do have a background in Microbiology and could go on for hours on my research and studies on gram negative enteric bacteria.
The human body, outside and inside are covered with 1,000 of species of bacteria, most of which is normal flora, the real risk comes if someone is carrying pathogenic species which in certain circumstances, can be passed on and cause a variety of ailments.
Every time our bodies come into contact with another, whether it be hugging, kissing, licking, sucking, fucking, cumming and such, transfer of bacteria occur.
Most is harmless to a healthy individual. Doesn't matter how much you clean and disinfect, the are still millions of bacteria present all over the human body.
Remember, next time you scratch an itch on your ass or crotch area, your fingers now have thousands of cfu's(colony forming units) of enteric bacteria (intestinal, fecal bacteria) spreading to every single thing you touch.
Don't worry though, most are harmless and the human body can handle it.
Now back to our regularly scheduled thread.