4.3.14 Consequences of Resistance Flashcards
What are the consequences of antibiotic 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 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
Commonly prescribed antibiotics are becoming less effective for many reasons, the main being:
Overuse of antibiotics and antibiotics being prescribed when not necessary
Large scale use of antibiotics in farming to prevent disease when livestock are kept in close quarters, even when animals are not sick
These factors have led to a reduction in the effectiveness of antibiotics, and an increase in the incidence of antibiotic resistance
These bacteria are commonly known as superbugs
The most common example is a strain of Staphylococcus aureus that has developed resistance to a powerful antibiotic called methicillin as well as other antibiotics (eg. penicillin) and is now known as MRSA (Methicillin-resistant Staphylococcus aureus)
Bacteria living where there is widespread use of many different antibiotics may have plasmids containing resistance genes for several different antibiotics, giving them multiple resistance and presenting a significant problem for doctors
In addition, resistance may first appear in a non-pathogenic bacterium, but then be passed on to a pathogenic species by horizontal transmission
There is a constant race to find new antibiotics as resistant strains are continuously evolving
How can we reduce antibiotic resistance and its impact?
Ways to prevent the incidence of antibiotic resistance increasing include:
Tighter controls in countries in which antibiotics are sold without a doctor’s prescription
Doctors avoiding the overuse of antibiotics, prescribing them only when needed (patients must only be given antibiotics when absolutely essential) – doctors should test the bacteria first to make sure that they prescribe the correct antibiotic
Antibiotics not being used in non-serious infections that the immune system will ‘clear up’ (patients must not keep unused antibiotics for self-medication of such non-serious infections in the future)
When prescribed a course of antibiotics, the patient finishing the entire course (even if they feel better after a few days) so that all the bacteria are killed, and none are left to mutate to become resistant strains
Antibiotics not being used for viral infections (antibiotics have no effect on viruses anyway, and this just provides an unnecessary chance for bacteria to develop resistance)
The use of ‘wide-spectrum’ antibiotics being reduced and instead those antibiotics that are highly specific to the infection (‘narrow-spectrum’ antibiotics) being used
The type of antibiotics prescribed being changed so that the same antibiotic is not always prescribed for the same infections and diseases (this reduces the chance of a resistant strain developing)
The use of antibiotics being reduced and more tightly controlled in industries such as agriculture – controls are now in place to limit their use in farming, where antibiotics are used to prevent, rather than cure, bacterial infections
The spread of already-resistant strains can be limited by:
Ensuring good hygiene practices such as handwashing and the use of hand sanitisers (this has reduced the rates of resistant strains of bacteria, such as MRSA, in hospitals)
Isolating infected patients to prevent the spread of resistant strains, in particular in surgical wards where MRSA can infect surgical wounds
What are the consequences of pesticide resistance?
Pesticide resistance in insects is a problem for the security of future food supplies for human populations, especially those that already face food shortages
Again, in a similar way to the use of antibiotics against bacteria, insecticides should be used sparingly or on rotation to avoid the evolution of resistance in pest insect populations
Using a combination of pesticides can delay the emergence and spread of resistance in pest insect populations
Farmers are also encouraged to use other forms of insect pest control, such as:
Biological control (introducing a natural parasite or predator of the pest insect)
Using crops that have been selectively bred or genetically modified to be pest-resistant