Table 1.

Four Generations of Cephalosporins

Generation	Examples	Activity	Miscellaneous
First	Cefazolin, cephalexin	Aerobic gram-positive bacteria, some community-acquired gram negative	Least expensive
Second	Cefoxitin, cefuroxime, cefotetan, cefaclor	Extended activity against gram negative. Cefoxitin has substantial activity against anaerobes	Decreased activity against gram positives
Third	Cefotaxime, ceftazidime, ceftriaxone, ceftizoxime	Most gram-negative bacteria, except Enterobacter and Citrobacter	Ceftriaxone has biliary excretion and is commonly used in biliary prophylaxis
Fourth	Cefepime	Like third generation with added stability against plasmid-borne β-lactamases	Does not induce β-lactamase capacity