Infectious Diseases - Medicines

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  • Infectious Diseases: Medicines
  • Chemicals vs pathogens
  • Antibiotic resistance
  • Developing medicines
  • Different types of medicines
  • Quiz

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Antibiotic resistance

The success of antibiotics has meant that they have been used increasingly over the last sixty years. They are not only used to treat humans, but also to treat sick animals. In the past antibiotics have been added to animal feeds to reduce infection and improve the growth of farm livestock; this use of antibiotics has been banned in the EU since 2006.

Bacteria frequently mutate and as a result strains of antibiotic-resistant bacteria have appeared. The widespread use of antibiotics has encouraged the appearance of these resistant strains of bacteria. The more often bacteria are exposed to an antibiotic, the bigger the risk that a resistant strain will evolve.

Often, after taking the antibiotics for just a few days, the symptoms of the infection can disappear. This is because the majority of the bacteria have been killed but a few will remain alive. These are the ones that have the greatest resistance to the antibiotic being used and stopping the treatment early gives them a chance to survive. They will reproduce so that the infection returns and this time all of the bacteria will be of the resistant type. These bacteria can be transmitted to others and treating the infection will require a different antibiotic.

Photo of agar plate which has half bacteria growing and half clear agar.

Developing antibiotic resistance
Photo courtesy of CDC

One such antibiotic resistant superbug is called MRSA (Methicillin-resistant Staphylococcus aureus). The bacteria is sometimes found in hospitals and can infect wounds following surgery or cause pneumonia. These infections can be serious and need treating with a range of antibacterial medicines. Hospitals work hard to maintain high standards of hygiene to prevent the outbreak of MRSA infections. Disinfecting surfaces and using antiseptic hand washes and gels help to prevent the spread of these infections.

Avoiding antibiotic resistance

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Antibiotic resistance

Only using antibiotics when they are absolutely necessary will help to stop the evolution of resistant strains of bacteria.

Another a simple way to reduce resistance is to make certain that any course of antibiotic treatment is completed.

Medicine that acts against bacterial infections. Penicillin is an example of an antibiotic.
Protein that is produced by lymphocytes (white blood cells) and that attaches to a specific antigen.
Molecule on the surface of a pathogen that identifies it as a foreign invader to the immune system.
Single-celled organism. Has a cell wall, cell membrane, cytoplasm. Its DNA is loosely-coiled in the cytoplasm and there is no distinct nucleus.
The use of biological organisms or enzymes to create, break down or transform a material
To cut apart, or separate, tissue especially for anatomical study.
Exponential growth
If something is growing exponentially the larger the quantity gets, the faster it grows
Micro-organism that can grow in long tubes called hyphae or as single cells. Fungi have a nucleus, cytoplasm and a cell wall.
Herd immunity
If a high percentage of a population is immune to a disease the disease cannot be passed on because it cannot find new hosts.
Infection caused by the human immunodeficiency virus (HIV). It attacks and destroys the immune system.
Hybridoma cells are formed by fusing a specific antibody-producing cell with a type of cancer cell that grows well in tissue culture
Immune system
The body's natural defence mechanism against infectious diseases.
A process which gives immune resistance to a particular disease. The human or animal is exposed to a harmless antigen in order to raise antibodies and provide an immune memory.
A type of white blood cell that make antibodies to fight off infections.
A type of white blood cell that consumes dead pathogens that have been killed by antibodies.
Organism that feeds off another living host and causes it some damage. An example of a parasite is a tapeworm that lives in the digestive system of a host organism.
A micro-organism that causes disease.
Phagocytes are the white blood cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells.
A polymer made up of amino acids joined by peptide bonds. The amino acids present and the order in which they occur vary from one protein to another.
Protozoa are one-celled animals
A spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavourable conditions.
A poisonous or toxic substance - produced by pathogens.
A small amount of dead or weakened pathogen is introduced into the body. It prepares the immune system to prevent future infections with the live pathogen.
Medicine that contains a dead or weakened pathogen. It stimulates the immune system so that the vaccinated person has an immunity against that particular disease.
The smallest of living organisms. Viruses are made up of a ball of protein that contains a small amount of the virus DNA. They can only reproduce after they have infected a host cell.
How well the drug works