Slide 1
An antibiotic needs a bacterial target
Antibiotics act on bacterial structures or processes. A useful target differs enough from the patient’s biology to make selective action possible.
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Bacteria have cell walls and molecular machinery that human cells do not share in exactly the same form. These differences create opportunities, but selective action does not mean a medicine has no adverse effects.
Slide 2
Some drugs weaken the bacterial cell wall
Some antibiotics interfere with construction of the bacterial cell wall. A weakened wall can leave the cell unable to withstand its physical conditions.
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Other medicines act on bacterial ribosomes, the structures that build proteins. Different drug classes therefore interrupt different essential jobs rather than all attacking one universal weak point.
Slide 3
Viruses do not use the same bacterial machinery
Viruses do not reproduce as independent bacterial cells. An antibiotic directed at a bacterial process will not automatically interrupt a viral infection.
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The useful question is whether the infectious agent has a susceptible target. Sharing symptoms such as fever or cough does not make two infections biologically equivalent.
Slide 4
One bacterium can resist one drug but respond to another
A bacterium can be susceptible to one antibiotic and resistant to another. The drug name alone does not establish whether a target can be reached.
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Cell envelopes can restrict entry, and microbial enzymes may disable a compound before it acts. Access to a target is as important as the target’s existence.
Slide 5
Beneficial bacteria can be affected too
Antibiotics can also affect harmless or beneficial bacteria. Their biological reach is broader than the particular microbe causing an illness.
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This ecological effect helps explain why choosing an antibiotic is a clinical decision about the likely organism, site and evidence. The mechanism does not supply an individual treatment recommendation.
Sources
- Mechanisms of Antibacterial Drugs
OpenStax, Rice University
- About Antimicrobial Resistance
CDC