antibiotics and other medicines

• Antibiotics 


  chemicals that kill or inhibit the growth of bacteria. They're used by humans as drugs to treat bacterial infections.
• antibiotics are useful because they can usually target bacterial cells without damaging human body cells.
• For the past few decades, we've been able to deal with bacterial infections pretty easily using antibiotics. As a result of this, the death rate from infectious bacterial disease has fallen dramatically.

  Despite their usefulness, there are risks to using antibiotics. For example, they can cause side effects and even severe allergic reactions in some people.
• There is genetic variation in a population of bacteria. Genetic mutations make some bacteria naturally resistant to an antibiotic.
• For the bacterium, this ability to resist an antibiotic is a big advantage. It's better able to survive in a host who's being treated with antibiotics to get rid of the infection, and so it lives for longer and reproduces many more times. This leads to the allele for antibiotic resistance being passed on to lots of offspring. It's an example of natural selection - see Figure 1. This is how antibiotic resistance spreads and becomes more common in a population of bacteria over time.
• Antibiotic resistance is a problem for people who become infected with these bacteria, because you can't easily get rid of them with antibiotics. Increased use of antibiotics means that antibiotic resistance is increasing. 'Superbugs' that are resistant to most known antibiotics are becoming more common.

  This means we are less able to treat some potentially life-threatening bacterial infections.
• • MRSA (meticillin-resistant Staphylococcus aureus) causes serious wound infections and is resistant to several antibiotics, including meticillin (which used to be called methicillin).
• Clostridium difficile infects the digestive system, usually causing problems in people who have already been treated with antibiotics.It is thought that the harmless bacteria that are normally present in the digestive system are killed by the antibiotics, which C. difficile is resistant to. This allows C. difficile to flourish. C. difficile produces a toxin, which causes severe diarrhea, fever and cramps.
• Developing new antibiotics and modifying existing ones are two ways of overcoming the current problem of antibiotic resistance.
• To reduce the likelihood of antibiotic resistance developing in the first place, doctors are being encouraged to reduce their use of antibiotics, e.g. not to prescribe them for minor infections and not to prescribe them to prevent infections (except in patients with already weak immune systems, e.g. the elderly or people with HIV). Patients are advised to take all of the antibiotics they're prescribed to make sure the infection is fully cleared and all the bacteria have been killed (which reduces the likelihood of a population of antibiotic-resistant bacteria developing).
• Scientists need to be constantly developing new drugs to target resistant strains of pathogens, as well as developing drugs for diseases that are currently incurable.
• Many medicinal drugs are manufactured using natural compounds found in plants, animals or microorganisms

  examples:

  • Penicillin is obtained from a fungus.
  • Some cancer drugs are made using soil bacteria.
  • Daffodils are grown to produce a drug used to treat Alzheimer's disease.
• Possible sources of drugs need to be protected by maintaining the biodiversity (the variety of different species) on Earth. If we don't protect them, some species could die out before we get a chance to study them.

  Even organisms that have already been studied could still prove to be useful sources of medicines as new techniques are developed for identifying, purifying and testing compounds.
• Personalised medicines 


  are medicines that are tailored to an individual's DNA.
• The theory is that if doctors have your genetic information, they can use it to predict how you will respond to different drugs and only prescribe the ones that will be most effective for you. Scientists hope that by studying the relationship between someone's genetic make-up and their responsiveness to drugs, more effective drugs can be produced in the future.
• Synthetic biology involves using technology to design and make things like artificial proteins, cells and even microorganisms. It has applications in lots of different areas, including medicine.