Antibiotic Resistance

Within a bacterial population, there is variation caused by mutations (as occurs in populations of all species)
A chance mutation might cause some bacteria to become resistant to an antibiotic (e.g. penicillin)
When the population is treated with this antibiotic, the resistant bacteria do not die
This means the resistant bacteria can continue to reproduce with less competition from the non-resistant bacteria, which are now dead
Therefore the genes for antibiotic resistance are passed on with a much greater frequency to the next generation
- As bacteria only have one copy of each gene, a mutant gene will have an immediate effect on any bacterium possessing it
Over time, the whole population of bacteria becomes antibiotic-resistant because the antibiotic-resistant bacteria are best suited to their environment
This is an example of evolution by natural selection
Some pathogenic bacteria have become resistant to penicillin as they have acquired genes that code for the production of the enzyme β-lactamase (also known as penicillinase), which breaks down penicillin

Antibiotic_resistance, IGCSE & GCSE Biology revision notes

Bacteria evolve rapidly as they reproduce and acquire random mutations, some of which confer resistance

Antibiotic-resistant strains are a major problem in human medicine
New resistant strains are constantly emerging due to the overuse of antibiotics
- By using antibiotics frequently, humans exert a selective pressure on the bacteria, which supports the evolution of antibiotic resistance
Scientists are trying hard to find new antibiotics that bacteria have not yet been exposed to, but this process is expensive and time-consuming
Some strains of bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), can be resistant to multiple antibiotics and they create infections and diseases which are very difficult to treat
When antibiotics were discovered, scientists thought they would be able to eradicate bacterial infections, but less than a century later a future is being imagined where many bacterial infections cannot be treated with current medicines

Antibiotic resistance in bacteria is an example of natural selection that humans have helped to develop through incorrect use or overuse of antibiotics
Implementation of certain measures can help to avoid antibiotic resistance. These measures may include:
- Avoiding prescription of antibiotics for non-serious or non-bacterial infections
- Maintaining high standards of hygiene in the hospital environment
- Minimising use of antibiotics for routine treatment of animals in agriculture
- Development of new types of antibiotic

The rise of antibiotic resistance presents significant challenges within the medical field, as it renders the treatment of specific illnesses more challenging and contributes to higher mortality rates
Addressing antibiotic resistance stands as a top priority for the World Health Organization (WHO)
The future effectiveness in treating common infections and minor injuries hinges upon the development of novel antibiotics
Presently, researchers are making use of chemical libraries to craft and produce fresh antibiotics
Within these screening libraries, there exists a wealth of information about numerous chemical compounds possessing antibacterial characteristics
Innovative methodologies like incorporating chemical libraries introduce promising avenues for countering the issue of antibiotic resistance

Antibiotic Resistance (HL IB Biology)