Oh... With all that extra info then, things look great.
The tissue sample will be more than enough for them to check what it is and if the antibiotic will work. (I worked at one of the labs they send samples like that too so I can guarantee if they check for one and see the other it will end up where it needs to be.)
The one shot given is pretty routine for general antibiotic in the meantime but if the results differ he can change it. So playing it safe in the meantime.
Fingers still crossed for you. I'm glad the heart isn't involved but that is still a scary area and a waiting game for you.