6.3.3Unit 6: Practical Skills in Biology II
Current Usage of Antibiotics — IAL Edexcel Linear Revision Notes & Topical Questions
5 min read 5 parts Lesson 15 of 48 Unit quiz
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Part 1 of 5Hospital-Acquired Infections
Definition
- Definition A hospital-acquired infection is one that a patient catches while in hospital.
Vulnerable patients
- Vulnerable patients Patients are often already ill and have weakened immune systems, so infection is more likely.
Poor hygiene
- Poor hygiene Spread increases when people do not wash their hands, cough or sneeze openly, or fail to disinfect equipment and surfaces.
Controls
- Controls Handwashing, isolating infected patients and disinfecting surfaces after each use reduce spread.
Why risk is high
- Why risk is high Many people with infections are gathered together, so pathogens pass easily between patients, staff and visitors.
Part 2 of 5Antibiotic Resistance
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Within a population of bacteria, mutation produces a few individuals with alleles that give resistance to an antibiotic.
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The antibiotic is a selection pressure that kills non-resistant bacteria.
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The resistant bacteria survive and reproduce with less competition.
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Resistant alleles are passed on, so the proportion of resistant bacteria rises.
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Resistance can also be passed between bacteria by horizontal gene transfer, and MRSA is a well-known example.
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The antibiotic does not cause the mutation; it only selects the bacteria that already carry the resistance allele.
Part 3 of 5Why Hospitals Are a Hotspot
Hospitals combine heavy antibiotic use with many vulnerable people.
Why Hospitals Are a Hotspot
Heavy use
- Heavy use Antibiotics are widely used in hospitals, which creates a strong selection pressure for resistance.
Close contact
- Close contact Many patients in one place makes transmission of resistant strains easy.
MRSA
- MRSA Methicillin-resistant Staphylococcus aureus is a strain of S. aureus resistant to the antibiotic methicillin.
Consequences
- Consequences Resistant infections are harder to treat and can lead to serious complications or death.
Horizontal transfer
- Horizontal transfer Resistance genes can move between bacteria, even of different species, so resistance can spread beyond the original strain.
Part 4 of 5Reducing Resistance
A narrow-spectrum antibiotic is effective against a limited range of bacteria, whereas a broad-spectrum antibiotic works against many types.
No unnecessary use
- No unnecessary use Antibiotics are not prescribed for minor infections or for viral diseases, since they do not work against viruses.
No prevention
- No prevention They are not used routinely to prevent infection.
Narrow spectrum
- Narrow spectrum Using narrow-spectrum antibiotics means that any resistance gene transferred to other bacteria is less likely to cause problems.
Rotation
- Rotation Rotating the antibiotics used reduces the selection pressure for resistance to any single drug.
Part 5 of 5Exam Checklist & Tips
6.3.3 – Key Points for the Exam
- Hospital-acquired infection An infection caught by a patient while in hospital.
- Selection pressure An environmental factor that affects survival and reproduction.
- MRSA A strain of Staphylococcus aureus resistant to methicillin and other antibiotics.
- Narrow-spectrum antibiotic An antibiotic active against only a limited range of bacteria.
- Horizontal gene transfer The passing of genes between bacteria that are not parent and offspring.
Common Mistakes
- Saying that bacteria become resistant because they choose to;
- resistance arises by mutation and natural selection.
- Writing that antibiotics create the mutations, when they only select resistant bacteria that already exist.
- Thinking people become resistant to antibiotics; it is the bacteria that become resistant.
- Forgetting to mention that antibiotics are ineffective against viral infections.
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