The good studies which have looked at the subject in
HIV discordant couples - couples where one person is
HIV positive and the other HIV negative - have shown zero transfer of HIV. There are anecdotal reports of people identifying oral sex as their only risk factor though these are very rare.
In repspect of your 2 g azithromycin, this will have dealt with primary syphilis, chlamydia, and probably gonorrhoea.