Except we have no reports of anyone being infected by someone who is on antibiotics. It is highly unlikely that any of us will be infected by someone who contracts anthrax and additionally all those exposed so far had first hand exposure from the letters. How do you explain resistance unless the anthrax was previously exposed it to anti-biotics ?
Will you relax?!
If you reread my post, it was in response to a general question about how organisms develop an tolerance to antibiotics, we weren't discussing anthrax. However, now that you mention it, naturally occurring bacteria, because of the ubiquitousness of penicillin, are known to develop resistance on their own. If the fact that the anthrax being investigated is beginning to show a resistance to penicillin is true, it would argue that the strain began as a naturally ocurring bug. Although that is not near to being conclusive.