Antibiotic
An antibiotic is a chemical substance, originally derived from microorganisms such as fungi or bacteria, that inhibits the growth of or kills bacteria by targeting bacterial-specific structures such as cell walls, ribosomes, or DNA replication machinery. Antibiotics have been among the most important medical discoveries of the 20th century, dramatically reducing mortality from bacterial infections. However, their overuse and misuse have accelerated the emergence of antibiotic-resistant strains, posing a major global health challenge.
Classes of Antibiotics and Their Mechanisms of Action
| Class | Example | Mechanism | Target Bacteria |
|---|---|---|---|
| Beta-lactams | Penicillin | Inhibits cell wall synthesis (PBP) | Gram-positive |
| Aminoglycosides | Streptomycin | Inhibits 30S ribosomal subunit | Gram-negative |
| Macrolides | Erythromycin | Inhibits 50S ribosomal subunit | Gram-positive |
| Fluoroquinolones | Ciprofloxacin | Inhibits DNA gyrase/topoisomerase IV | Broad spectrum |
| Tetracyclines | Doxycycline | Inhibits 30S ribosomal subunit | Broad spectrum |
Interactive Tools
Wikimedia Commons, CC BY-SA
Related Terms
Antibiotic Resistance
Antibiotic resistance is the ability of bacteria to survive and multiply in the presence of an antibiotic that would normally inhibit or kill them, arising through genetic mutations or acquisition of resistance genes via horizontal gene transfer. It develops because antibiotics exert selective pressure on bacterial populations, favouring the survival and proliferation of resistant strains. The World Health Organization (WHO) considers antibiotic resistance one of the greatest global public health threats, as it renders standard treatments ineffective and increases the risk of fatal infections.
Bacteria
Bacteria are single-celled prokaryotic microorganisms that lack a membrane-bound nucleus and reproduce primarily by binary fission. They are among the most abundant life forms on Earth, inhabiting nearly every environment including soil, water, and the human body. Bacteria play essential roles in nutrient cycling, decomposition, and digestion, and certain species cause infectious diseases while others are harnessed in biotechnology and food production.
Pathogen
A pathogen is any biological agent — including bacteria, viruses, fungi, parasites, or prions — that causes disease in a host organism. Pathogens cause harm by directly destroying host cells, releasing toxins, or triggering damaging immune responses. Understanding pathogen biology is the foundation of epidemiology, vaccine development, and the design of antimicrobial therapies.
From Greek "anti-" (ἀντί) meaning "against" and "bios" (βίος) meaning "life". The term "antibiotic" was coined by microbiologist Selman Waksman in 1942 to describe substances produced by microorganisms that inhibit the growth of other microorganisms, following Alexander Fleming's 1928 discovery of penicillin.