[The bacterial cell wall and penicillin resistance: facts, questions and hopes]

The simplest conceivable event at the level of the gene can result in the emergence of antibiotic-resistant determinants. The bacterial world behaves as an enormous organism the cells of which exchange their genes with great ease and, likewise, the opportunities for the exchange of genetic material in nature is, probably, limitless. This knowledge cannot be ignored. It leads to the important conclusion that the antibiotics are societal drugs. A resistance gene which has appeared somewhere in the world can travel far and fast.