Antibiotic resistance

how does antibiotic resistance first occur and examples

Resistance first develops due to a mutation. Bacteria reproduce asexually, so all the offspring should be the same, but sometimes, at random, mutations occur when DNA is replicated. This normal leads to it being fatal but can lead to resistance.

1. A mutation could slightly alter an enzyme, changing its substrate specificity so that its active site will now bind penicillin. Some bacteria now have penicillinase enzymes that modify or break down penicillin, rendering the antibiotic useless.

2. Antibiotics are often similar to normal bacterial metabolites, and a small mutation in an existing enzyme can modify its active site to fit an antibiotic.

3. A mutation could modify a transport protein so that the antibiotic is transported out of the bacterial cell, or not transported into the bacterial cell. · A mutation could slightly alter a ribosome so that antibiotics like tetracycline and streptomycin can no longer bind and inhibit protein synthesis.

these mutations are rare but what factors about bacteria means these mutation can occur quite often

As they reproduce so rapidly there are many chances for error in replication of DNA.

how does natural selection play a role

the antibiotic act as a selection pressure those which are have the mutation are able to survive are reproduce by binary fission therefore the frequency of the mutation increases. Those without die and are unable to survive to reproduce.

explain conjugation

A conjugation tube can form between the 2 cells. DNA passes from the donor cell to the recipient cell normally plasmids are shared. These plasmids normally have advantageous genes such as antibiotic resistance.

what can conjugation cause

multiple antibiotic resistance

what are some some ways to control antibiotic resistance.

1. uses a wider range of antibiotic’s + find more

2. limit the use of antibiotics

3. stop using antibiotics in food for animals

4. improve hospital hygiene

5. screen and isolate patients to prevent the spread.

steps 2,3 used as they cause antibiotics to be a selection pressure.