Which of the following is a fourth-generation cephalosporin?

Cefepime is classified as a fourth-generation cephalosporin, and understanding its development and characteristics helps to highlight why it holds this classification. Fourth-generation cephalosporins were designed to provide enhanced coverage against gram-negative bacteria, particularly Pseudomonas aeruginosa, while also maintaining effectiveness against gram-positive organisms.

Cefepime exemplifies this by exhibiting a broad spectrum of antimicrobial activity, which makes it particularly useful in treating serious infections in hospital settings. It has improved penetration into the outer membrane of gram-negative bacteria compared to earlier generations, which contributes to its efficacy against resistant strains.

The other choices represent different generations of cephalosporins: Cefdinir and Cefpodoxime are third-generation cephalosporins, which offer good activity against gram-negative bacteria but have a narrower spectrum than Cefepime. Ceftriaxone, also a third-generation cephalosporin, is widely used but does not have the comprehensive coverage and potency against certain resistant infections that Cefepime provides. Therefore, Cefepime's broader spectrum and enhanced characteristics are why it is appropriately classified as a fourth-generation cephalosporin.