In the process of evolution, bacteria have acquired well-developed
mechanisms of resistance to an extensive array of hostile substances.
This time-tempered system of defense is so intricate and adaptable that
contemporary medicine has been hard-pressed to maintain an advantage.
In this article, the processes responsible for bacterial resistance to
extended-spectrum cephalosporins are reviewed. Particular emphasis is
placed on the extended-spectrum β-lactamases that have emerged to
provide bacteria with formidable resistance to modern drugs. Avoidance
of this problem requires limitations on extended-spectrum cephalosporin
usage. While carbapenems are clearly the treatment of choice for
infections caused by these pathogens, empirical use of
β-lactam/β-lactamase inhibitors such as piperacillin/tazobactam has
been associated with reduction in the prevalence of cephalosporin