IIRC urine can’t kill bacteria in a wounds, soldiers used it as the last resort when there are no clean water to clean open wounds, since urine contains no germs (but to make sure that your urine does not subject to bacteria in the urethra, you have to use mid-stream urine :p).
Edit: Upon further research, I found out that urine contains salt, which can kill bacteria. But the urine itself also have harmful chemicals ( sodium and mineral) your body excreted , so reintroduce harmful chemicals back into your body isn’t a very good idea.