Extended-spectrum (second- and third-generation) cephalosporins.

The extended-spectrum cephalosporins provide better activity against gram-negative bacilli and anaerobes than first-generation agents. Cefoxitin and cefotetan (second-generation) and ceftriaxone (third-generation) have excellent activity against B. fragilis and are useful in the treatment of postoperative infections and pelvic inflammatory disease. The extended-spectrum cephalosporins are as efficacious as first-generation agents for prophylaxis of cesarean section and hysterectomy. The first-generation drugs, such as cefazolin, are considerably less expensive than these newer compounds, however, making first-generation agents the drugs of choice when used for prophylaxis. The majority of the third-generation agents should be reserved for the treatment of meningitis and resistant nosocomial infections.