How resistance develops
After Alexander Fleming discovered penicillin in 1928, antibiotics dramatically cut deaths from infections such as pneumonia and sepsis. Yet in his 1945 Nobel lecture Fleming warned that under-dosing would let microbes become resistant. When an antibiotic is used, susceptible bacteria die and the few that survive thanks to chance mutations multiply. Bacteria can also hand small loops of DNA called plasmids to other species, so resistance genes spread quickly. Mechanisms include enzymes that destroy the drug (such as beta-lactamases), altered drug targets, and pumps that push the drug out of the cell.
Superbugs and the toll
Bacteria that resist many antibiotics at once are often called superbugs. Examples include methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), carbapenem-resistant Enterobacterales (CRE) that defeat a last-resort drug class, and multidrug-resistant tuberculosis. A 2022 Lancet analysis estimated that about 1.27 million people died in 2019 as a direct result of resistant infections. South Korea's antibiotic use is among the higher levels in the OECD, and hospital CRE reports have risen steadily. Antibiotics used in livestock and fish farming are another important source of resistant bacteria.
What individuals can do
Colds and most sore throats and acute bronchitis are caused by viruses, which antibiotics cannot treat. Using antibiotics for viral infections brings no benefit, disrupts the gut microbiome and can breed resistant strains. Take prescribed antibiotics at the dose and duration your clinician sets, and never save leftovers to self-treat later or share them. Newer research shows many infections can be treated with shorter courses, so do not shorten or extend a course on your own; ask your doctor. Handwashing and vaccination reduce infections in the first place and therefore antibiotic use.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- Will antibiotics help me get over a cold faster?
- No. Colds are viral, so antibiotics do not work. A doctor may prescribe them only if a bacterial complication such as an ear or sinus infection is suspected.
- Can I stop antibiotics once I feel better?
- Don't stop on your own; follow the prescription. Some infections can be treated with shorter courses, but your doctor should make that call.
Sources reviewed: 2026-10-26
References
- Fleming, A. (1945). Penicillin. Nobel Lecture, December 11, 1945.
- Antimicrobial Resistance Collaborators. (2022). Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis. The Lancet, 399(10325), 629–655.
- World Health Organization. (2015). Global Action Plan on Antimicrobial Resistance. WHO.
- O'Neill, J. (2016). Tackling Drug-Resistant Infections Globally: Final Report and Recommendations. Review on Antimicrobial Resistance.