How do cephalosporins work and what are their generations?

Cephalosporins are beta-lactam antibiotics that work by the same mechanism as penicillins, inhibiting bacterial cell wall synthesis. They are organized into five generations with progressively broader gram-negative coverage. First-generation agents like cefazolin cover gram-positive organisms well. Second-generation agents like cefuroxime add some gram-negative coverage. Third-generation agents like ceftriaxone have strong gram-negative activity. Fourth-generation agents like cefepime cover both. Fifth-generation agents like ceftaroline cover MRSA.