Doc, 5 week ago i have unprotect oral with sex worker and tested negative on elisa, do i exposure to the hiv since i positive chlamydia on same test?

Unlikely but...: You're very unlikely to catch HIV from oral sex, though you can catch other nasty things. If you are horribly worried, you can get a pcr for the HIV viruses. Good luck, and love wisely in the future.

Male or female?: If you had oral sex by fellatio (penis into your mouth) and they ejaculated this is an excellent way to get a variety of stds, including hiv, gonorrhea and syphilis among others. If you went down on a woman and had cunnilingus and had no open wounds in your mouth or on lips, then the risk is almost non-existent. Make sure you do follow-up testing.