β-lactam antibiotics are a class of broad-spectrum antibiotics that include penicillins, cephalosporins, carbapenems, and monobactams, characterized by the presence of a β-lactam ring in their molecular structure. They work by inhibiting bacterial cell wall synthesis, making them highly effective against a wide range of Gram-positive and Gram-negative bacteria, but their efficacy can be compromised by bacterial β-lactamase enzymes that confer resistance.