ABSTRACT
These semisynthetic penicillins are described together because historically they were referred to as “newer antipseudomonal penicillins.” They are all vulnerable to the action of many beta-lactamases, but most of them are considerably more active in vitro than carbenicillin and ticarcillin against Pseudomonas aeruginosa, other Gram-negative bacteria, and some Gram-positive bacteria. These drugs are acylamino penicillins. Because mezlocillin and azlocillin each contain a ureido (-N-CO-N-) group, they are called ureido-penicillins (Slack, 1981; Selwyn, 1982). Piperacillin is now the key drug in this group and is commonly available, either alone or in the fixed combination of piperacillin–tazobactam (see Chapter 17, Piperacillin–tazobactam).
