The newer cephalosporins. Aztreonam and imipenem.

Many of the antimicrobial agents described here exhibit great advances over older drugs in terms of antimicrobial spectrum, clinical utility, and, sometimes, safety. The newer cephalosporins are useful for treatment of many common outpatient and inpatient infections. Aztreonam provides excellent coverage against a broad range of aerobic gram-negative bacteria, without the toxicity associated with aminoglycosides. Imipenem exhibits activity against an impressive array of pathogens. These antimicrobials are expensive, however, and some offer no advantages over older agents. Finally, all--including imipenem--are faced with increasing resistance of bacteria.