What is the difference between bactericidal and bacteriostatic antibiotics?

Bactericidal antibiotics kill bacteria directly, while bacteriostatic antibiotics inhibit bacterial growth and reproduction, relying on the patient's immune system to eliminate the organisms. Penicillins, cephalosporins, fluoroquinolones, and aminoglycosides are bactericidal. Macrolides, tetracyclines, and sulfonamides are generally bacteriostatic. The distinction matters most in immunocompromised patients who may need bactericidal agents because their immune system cannot clear inhibited bacteria. In patients with normal immune function, both types are effective.