1.3 Types of antibiotic

Antibiotics may be active against a wide range of bacteria (broad-spectrum) or just a few types (narrow-spectrum). Additionally, antibiotics either kill bacterial cells (bactericidal) or stop them growing and dividing (bacteriostatic).

Factors that determine the spectrum of antibiotic activity include:

• ability to penetrate the bacterial cell – since most bacterial targets are located in the cell’s interior
• how widespread the target is among different bacterial species
• bacterial resistance to the antibiotic.