Cephalosporins

Chemical Structure / Formula of Cephalosporins

• Core Structure: β-lactam ring fused to a dihydrothiazine ring (unlike penicillins, which have a thiazolidine ring).
• Different generations have variable side chains affecting their spectrum of activity.

Mechanism of Action

• Similar to penicillins: inhibit bacterial cell wall synthesis by targeting penicillin-binding proteins (PBPs), leading to bacterial lysis.
• More resistant to β-lactamases compared to penicillins.

Uses of Cephalosporins

• First-generation: Gram-positive coverage (Staphylococcus, Streptococcus).
• Second-generation: Increased Gram-negative activity (Haemophilus, Enterobacter).
• Third-generation: Broad-spectrum, effective against resistant Gram-negative bacteria (Pseudomonas, Neisseria).
• Fourth/Fifth-generation: Advanced activity against MDR bacteria and MRSA (Fifth-generation).

Side Effects

• Common: Diarrhea, nausea, rash.
• Serious: Hypersensitivity reactions, C. difficile infection, nephrotoxicity (rare).

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