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.
Key Mechanisms of Antibiotic Resistance in Bacteria
| Mechanism | Description | Example Antibiotic Affected | Example Bacterium |
|---|---|---|---|
| Enzymatic inactivation | Beta-lactamase destroys beta-lactam ring | Penicillin | MRSA |
| Efflux pumps | Actively pumps antibiotic out of cell | Tetracycline | E. coli |
| Target modification | Alters ribosomal binding site | Erythromycin | S. pneumoniae |
| Reduced permeability | Loss of outer membrane porins | Carbapenems | P. aeruginosa |
| Bypass pathway | Acquires alternative metabolic pathway | Trimethoprim | S. aureus |
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Related Terms
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.
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.
"Antibiotic" from Greek "anti-" (against) + "bios" (life); "resistance" from Latin "resistere" (to stand against). The phenomenon was observed almost immediately after penicillin was introduced clinically in the 1940s, when Alexander Fleming himself warned in his 1945 Nobel Prize lecture that misuse of penicillin could lead to resistant bacteria.