Treatment of gram-negative infections in patients with renal impairment: new alternatives to aminoglycosides.

Aminoglycosides have become an indispensable component in the armamentarium against serious gram-negative infections. In spite of the availability of effective guidelines for prevention, the frequency of toxic side effects associated with aminoglycoside therapy is an impetus for the substitution of safer and equally efficacious alternatives, particularly in the setting of renal impairment. Recently, three new classes of antibiotics with potent gram-negative activity have become available. These are the monobactams, the carbapenems, and the fluorinated 4-quinolones. The antimicrobial spectrum of aztreonam, a monobactam, closely resembles that of aminoglycosides. Imipenem, a carbapenem, is a broad spectrum antibiotic with activity against gram-negative aerobes as well as gram-positive aerobes and many anaerobes. Ciprofloxacin, an orally active quinolone, has gram-positive and gram-negative coverage against aerobes but not anaerobes. These agents offer an alternative therapeutic option to aminoglycosides and, in the setting of pre-existing renal impairment, are particularly attractive in view of their safety.