An antibiotic is a type of antimicrobial substance active against bacteria. It is used to treat bacterial infections. Antibiotics can either kill bacteria (bactericidal) or inhibit their growth (bacteriostatic).

The term "antibiotic" was originally used to refer to substances produced by microorganisms that inhibit the growth of other microorganisms. However, with the advent of synthetic antimicrobials, the term now also includes synthetic drugs that have antibacterial activity.

Antibiotics are among the most frequently used medications and are vital for treating many bacterial infections. However, the overuse and misuse of antibiotics have led to the development of antibiotic-resistant bacteria, which poses a significant threat to public health.

Here are some key aspects of antibiotics:

• Mechanism of Action: Antibiotics work by targeting essential bacterial processes, such as cell wall synthesis, protein synthesis, DNA replication, or other metabolic pathways.
• Spectrum of Activity: Antibiotics can have a broad spectrum (effective against a wide range of bacteria) or a narrow spectrum (effective against specific types of bacteria).
• Administration: Antibiotics can be administered orally, intravenously, or topically, depending on the type of infection and the severity.
• Resistance: Bacteria can develop resistance to antibiotics through various mechanisms, such as mutations, enzymatic inactivation of the antibiotic, or efflux pumps that remove the antibiotic from the bacterial cell.

For more detailed information, you can refer to these resources:

• World Health Organization - Antibiotic resistance
• Centers for Disease Control and Prevention - Antibiotic Use