I recently visited a sex worker in Northern California. She is from Taiwan.  We started protected vaginal sex with a condom. Everything was fine and I ejaculated. When I pulled out, I noticed the condom ripped and the tip of my penis was exposed. The sex lasted about 3 minutes. Afterwards I washed my penis and groin area with soap and water. She told me she gets tested every 3 months and assured me she is disease free. I told her this is the first time this has happened to me and I was scared.  She told me she gets tested regularly because she wants to take care of her health. I used the Okamoto 004 condom and I am uncircumcised.  My questions are: what is my risk for this? How soon can I get an HIV test? Should I go on PREP?  Thank you again for your time.

This was a very low risk encounter.  Most commercial sex workers do not have STIs, including HIV because they are aware of the risks of infection from their clients and they tend to test regularly.  Your partner has assured you that this is the case for her.  Even in the unlikely circumstance that she had HIV, your risk for infection from your encounter is, on average, less than 1 in 1000.  I do not feel that PEP is needed here and if I was seeing you in clinic, I would not prescribe the medications for you.  

In terms of testing, the fastest way to prove that you were not infected is to get an HIV RNA PCR test some time more than 11 days after your exposure.  At this time, test results will be conclusive.  Results of a 4th generation, HIV antigen/antibody test will not be fully conclusive until at least 6 weeks following the encounter.

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I hope that this information is helpful. Please don't worry.  EWH

In terms of HIV risk I would not worry at all about resuming unprotected sex with your regular partner.  The risk for other, more common STIs is also quite low and could be entirely ruled out by getting a urine test for gonorrhea and chlamydia at this time.  

I hope this information is helpful.  EWH