I thought the “long held” beliefs language was a little strong. I doubt many scientists believed that there existed no new classes of agents that were antibiotics. Most believed we had not discovered any for quite a while. Those are two very different beliefs.
Oh, no way. Settled science - no debating! LOL
Have a look at TETRAPHASE PHARMACEUTICALS (NASD:TTPH). They have some very promising variations of tetracycline under development.