Answer:
When patient takes in antibiotics the resistance bacteria gets a competitive survival advantage over the normal sensitive bacteria and hence grows faster.
Explanation:
- Bacteria can acquire resistance by taking in plasmids containing MDR (Multi-Drug Resistance) gene cassettes. The MDR genes produces proteins that can:
- Render the antibiotic ineffective to act on its target by inducing chemical modifications on the drug.
- Promote efflux of the drug from the bacterial cell so that the drug cannot act upon its target.
- When a healthy person ( having no prior exposure to the antibiotic) is infected by bacteria ( both sensitive and resistant varieties):
- A competition develops for the host cells and nutrients between the sensitive and the resistant variety.
- This mutual competition restricts either of the sensitive or resistant bacterial strain to grow profusely.
- When a person (having prior antibiotic exposure), gets infected by bacteria ( both sensitive and resistant varieties) and is exposed to the same antibiotic:
- The sensitive variety, due to its sensitivity towards the drug, gets killed.
- The resistant variety, due to its MDR genes, bypasses the lethal effect of the drug and survives.
- These surviving resistant bacteria can now infect all the available host cells and utilise all the available nutrients without facing any competition and multiply rapidly.
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