Ceftriaxone is a member of which generation of cephalosporins?

• A. 1st gen
• B. 2nd gen
• C. 3rd gen
• D. 4th gen

Answer: (C)

Cephalosporin generations reflect how their antimicrobial spectrum shifts as you move from older to newer drugs. Early generations excel at Gram-positive coverage, while later generations broaden activity against Gram-negative bacteria and improve ability to reach the central nervous system.

Ceftriaxone is a third-generation cephalosporin because it expands Gram-negative coverage compared with earlier generations and penetrates the CNS well, making it effective for meningitis and other serious infections caused by gram-negative organisms. Its Gram-positive activity is generally weaker than that of first- or second-generation cephalosporins, which is consistent with the generation shift toward broader Gram-negative activity and preserved CNS penetration.

In contrast, first-generation cephalosporins are superb for Gram-positive cocci but limited against Gram-negative bacteria; second-generation drugs add more Gram-negative coverage but still don’t match the breadth of the third generation; fourth-generation agents like cefepime push even wider Gram-negative activity (including some Pseudomonas) and retain good CNS penetration. So ceftriaxone fits best with the third generation.