00 · IN THREE MINUTES
The answer in three steps
- 1Mutation and create variation before and during exposure.
- 2An antibiotic removes susceptible competitors more effectively than resistant cells.
- 3Survivors multiply and resistance genes spread through populations, hosts and environments.
01 · VARIATION COMES FIRST
Variation comes first
DNA replication produces mutations without regard to need. Bacteria can also receive resistance genes on plasmids and other mobile elements from related or sometimes distant lineages.
02 · THE DRUG CHANGES RELATIVE SUCCESS
The drug changes relative success
A resistant cell may be rare before exposure. When an antibiotic suppresses susceptible cells, that variant can survive, reproduce and become a larger fraction of the population.
Variation comes first
DNA replication produces mutations without regard to need. Bacteria can also receive resistance genes on plasmids and other mobile elements from related or sometimes distant lineages.
genetic variationThe drug changes relative success
A resistant cell may be rare before exposure. When an antibiotic suppresses susceptible cells, that variant can survive, reproduce and become a larger fraction of the population.
selectionResistance has several mechanisms
Bacteria can alter a drug target, destroy or modify the molecule, reduce entry, pump it out or bypass the blocked pathway. One strain may accumulate several mechanisms.
mechanismSelection extends beyond one patient
Use in human medicine, animals and agriculture, along with wastewater and transmission in communities and hospitals, shapes the ecological network through which resistance moves.
transmission network03 · RESISTANCE HAS SEVERAL MECHANISMS
Resistance has several mechanisms
Bacteria can alter a drug target, destroy or modify the molecule, reduce entry, pump it out or bypass the blocked pathway. One strain may accumulate several mechanisms.
04 · SELECTION EXTENDS BEYOND ONE PATIENT
Selection extends beyond one patient
Use in human medicine, animals and agriculture, along with wastewater and transmission in communities and hospitals, shapes the ecological network through which resistance moves.
05 · EVOLUTION DOES NOT MAKE EVERY INFECTION UNTREATABLE
Evolution does not make every infection untreatable
Resistance is specific to a drug and organism, can carry fitness costs and may decline when selection changes. Yet genes can persist and return, so stewardship and surveillance matter.
06 · SOURCES AND EVIDENCE
Sources and evidence
The explanation follows the evidence chain below. Links open the original source.
- 01Antimicrobial resistanceOFFICIAL DATA / TECHNICAL REPORT ↗
Supports a specific claim or evidence boundary used in this article.
- 02About Antimicrobial ResistanceINSTITUTIONAL EXPLAINER ↗
Supports a specific claim or evidence boundary used in this article.
- 03The origins and molecular basis of antibiotic resistancePEER-REVIEWED REVIEW ↗
Supports a specific claim or evidence boundary used in this article.