Slide 1
Microbes become resistant, not the patient’s body
Antimicrobial resistance means a microbe can withstand a drug intended to act against it. It is not the patient’s body becoming resistant.
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A bacterial population can contain genetic variation before exposure. When susceptible cells are removed or suppressed, variants with a survival advantage can become more common.
Slide 2
Bacteria can change targets, block entry or remove drugs
A bacterium may alter a drug’s target, keep the drug out or remove it. Different resistance mechanisms solve different molecular problems.
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Efflux pumps export compounds from the cell. Other mechanisms chemically inactivate a drug, showing that resistance need not involve changing the structure the drug originally targeted.
Slide 3
Resistance genes can pass between bacteria
Resistance genes can pass between bacteria as well as from parent to offspring. Evolution is not limited to a single family line.
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Mobile genetic elements can carry more than one resistance determinant. This allows selection acting on one trait to help maintain other linked traits in the same population.
Slide 4
Resistant organisms can then spread between hosts
Resistant organisms can move among people, animals and environments. Selection and transmission are related but distinct parts of the problem.
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Reducing infections limits both spread and the need for antimicrobial treatment. Prevention changes the conditions in which resistance expands, not merely the choice of a drug after illness occurs.
Slide 5
Laboratory testing tracks which drugs still work
Laboratories test susceptibility to learn which drugs still affect an organism. Resistance patterns can change across places and over time.
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A result from one isolate does not describe every member of a species everywhere. Surveillance combines many observations to detect broader changes while retaining the local context.
Sources
- Antimicrobial Resistance: Causes and How It Spreads
CDC
- Drug Resistance
OpenStax, Rice University