Group of cephalosporin antibiotics capable of killing aerobic gram-negative rods. These agents are commonly used for treatment of pneumonia and meningitis. Some agents, namely ceftazidime and cefoperazone, have excellent activity against Pseudomonas aeruginosa. Examples of third-generation cephalosporins are cefsulodin, cefotaxime, ceftizoxime, ceftriaxone, cefoperazone, moxalactam, and ceftazidime.