Which of the following is NOT a third-generation cephalosporin?

Cefepime is not a third-generation cephalosporin; it is actually classified as a fourth-generation cephalosporin. Fourth-generation cephalosporins like cefepime are developed to have a broader spectrum of activity compared to their predecessors and are effective against a wider range of gram-positive and gram-negative bacteria, including Pseudomonas aeruginosa. This is distinct from third-generation cephalosporins, which typically focus more on improving activity against gram-negative organisms and less on gram-positive bacteria.

In contrast, the other options—cefpodoxime, cefixime, and cefdinir—are indeed all third-generation cephalosporins. They are designed to combat certain bacteria with enhanced effectiveness but do not have the broader range that fourth-generation options like cefepime exhibit. Understanding these classifications helps in appropriately selecting antibiotics for treating specific infections.