Shared a kiss with a stranger at a nightclub.
During the kiss realised there was blood in our mouth.
Am I at risk of infection?
Theoretically there is a risk of acquiring HIV from kissing with blood present, but both partners would need to have open, actively bleeding wounds in the mouth for there to be any possibility of transmission. Kissing with no blood present is a no risk activity because saliva does not pass the virus - in fact, saliva offers some protection against HIV, and this helps lower your risk even further. There are no recorded cases of anyone acquiring HIV from kissing (even from deep kissing or kissing with blood present).
Testing is not necessary based off of this experience alone, but if you are sexually active or have not been tested recently then you may choose to do so. I hope that this information reassures you.