Understanding Bacteria & Medicines
Understanding Bacteria & Medicines
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Understanding Bacteria & Medicines
What do you already know about bacteria and antibiotics?
Learning Objective
At the end of the lesson you will be able to explain the roles of bacteria in human disease, describe how antibiotics and other medicines work, and discuss the significance of antibiotic resistance and the importance of biodiversity in drug discovery.
Bacteria as Pathogens
Bacteria can cause diseases in humans through varied mechanisms such as producing toxins or invading host cells.
Staphylococci: Exotoxin Producers
Staphylococci release exotoxins, soluble proteins that are part of their metabolism and can be very toxic to the host.
Salmonella: Endotoxin Producers
Salmonella are gram-negative bacteria. Their outer membrane releases endotoxins (lipopolysaccharides) causing inflammation and fever.
Mycobacterium and TB
Mycobacterium tuberculosis can invade macrophages and lie dormant, protected by thick waxy cell walls. This helps TB persist and cause long-term infection.
What are Antibiotics?
Antibiotics are medicines that target and kill or inhibit bacteria, without harming human cells. Penicillin was the first discovered antibiotic.
Types of Antibiotics
Bactericidal
Bacteriostatic
Kill bacteria by destroying cell walls. Example: Penicillin.
Prevent growth and reproduction of bacteria. Example: Tetracycline.
Discovery of Penicillin
Penicillin, derived from fungus, was discovered by Alexander Fleming in 1928 and revolutionised treatment for bacterial infections.
How Do Antibiotics Work?
Antibiotics target structures unique to bacteria, like cell walls or enzymes for DNA replication, leaving human cells unharmed.
Antibiotic Resistance
Antibiotic resistance happens when bacteria mutate, survive antibiotic use, and reproduce. Overuse and misuse of antibiotics accelerate this process.
Examples of Resistant Bacteria
MRSA
C. difficile
Methicillin-resistant Staphylococcus aureus: Causes skin and joint infections. Resistant to many common antibiotics.
Infects the gut when normal bacteria are removed. Grows after antibiotic treatments, causing serious diarrhea.
Dangers of Antibiotic Resistance
Resistant infections are harder to treat, especially in hospitals. This can threaten the health of vulnerable patients and increase healthcare costs.
Preventing Antibiotic Resistance
Hospitals can limit antibiotic prescriptions, isolate infected patients, and enforce strict hand hygiene to prevent the spread of resistant bacteria.
Testing Antibiotic Effectiveness
Bacterial cultures with antibiotic discs on agar plates show zones of clearing, indicating antibiotic effectiveness.
Aseptic Techniques in Labs
Disinfect work areas, use sterile equipment, and work near a Bunsen burner to avoid contamination during experiments with bacteria.
Other Sources of Medicines
Many medicines are derived from natural compounds found in plants, animals, or microorganisms. Biodiversity helps in the discovery of new drugs.
Examples of Natural Medicines
Aspirin originates from willow bark. Penicillin comes from fungus. St John’s Wort acts as an antidepressant.
The Importance of Biodiversity
Protecting ecosystems ensures access to new natural compounds, which could lead to future medical discoveries and novel treatments.
Personalised Medicines
Modern medicine increasingly focuses on treatments tailored to an individual's DNA, leading to more effective and safer care.
Synthetic Biology in Medicine
Synthetic biology allows us to engineer cells or organisms to create new drugs, like T cell receptors for cancer treatment or bacteria programmed to target tumours.
Lesson Summary
You have learned about bacterial mechanisms, how antibiotics and other medicines work, the issue of antibiotic resistance, and the role of biodiversity and modern technology in drug development.
Write down 3 things you learned in this lesson.
Write down 2 things you want to know more about.
Ask 1 question about something you haven't quite understood yet.
