antibiotic resistance- lqc 8b

Question 1

why are bacteria becoming resistant to antibiotics?

Answer 1

The presence of an antibiotic provides a selection pressure for the bacteria. There is some naturally occurring genetic variation in the bacterial population. A random mutation created a new allele for resistance. Those bacteria that do not possess the allele for resistance are selected against and are more likely to be destroyed. Those which possess an advantageous allele are selected for; they are more likely to survive and reproduce. The advantageous allele may be for a new enzyme that can breakdown/destroy the antibiotic, a cell membrane protein that pumps out the antibiotic or for a new metabolic pathway that bypasses the reactions inhibited by the antibiotic. The frequency of the allele in the bacterial population will increase. The allele can be passed via vertical evolution to ‘offspring’ and/or horizontal evolution to other bacteria of the same or different species via conjugation.

Question 2

give two examples of multi drug resistant bacteria

Answer 2

TB, MRSA

Question 3

Outline the measures hospitals use in controlling the development of multi-drug resistant bacteria and their spread

Answer 3

There are strict codes of practice that need to be followed:
1. Handwashing: Hand wash stations are at the entrance to every ward and alcohol gel at the end of every patient bed. Signs are put up reminding all hospital personnel and visitors to wash their hands.
2. Clothing & personal items: Doctors & nurses have rules preventing them from wearing watches, ties and long sleeves.
3. Antibiotic use: These are only prescribed when the patient is definitely suffering from a bacterial infection. The antibiotic prescribed must be targeted against the bacterium causing the infection. The use of prophylactic antibiotics (those prescribed in case of an infection) is strictly controlled. Patients are educated and advised to complete their full course of antibiotics even when they feel better so that all the bacteria are destroyed. Different antibiotics should be used for repeat infections.
4. Cleaning: Regular deep cleaning and normal daily cleaning of toilets, hospital ward floors, equipment i.e. bedpans, bedframes. Patient gowns and bedding needs to be changed regularly.
5. Screening & isolation of patients: This can identify patients who may carry a drug-resistant bacterium (i.e. MRSA) into the hospital. Patients found to have drug-resistant infections should be kept apart from other patients in private rooms.
6. Monitoring: It has been made mandatory that hospitals measure and report on levels of drug-resistant infections.