9F-evolving pathogens Flashcards
What has led to the emergence of antibiotic-resistant bacteria?
Inappropriate use and overuse of antibiotics.
How have bacteria responded to the use of antimicrobial agents and antibiotics?
Bacteria have developed resistance against antimicrobial agents and antibiotics.
Explain the variabilty, selection pressure, selective advantage and herbailty of bacteria
- variation- a populaiton of bacteira has individuasl resistant to an antibioticas well as indiviudals susceptible to antibitoics
2.selection pressures- exposure to an antibiotic serves as an enviornmentla sleection pressure
3.selective advnatgae- a selective advantageis conferred to bactiera with resistance to antibitoics
4.Heritabilty- bacteria resistant to antibiotics are able to continue replicating nad and pass on the allele for resistance to other bactiera via bacteiral conjugation, increasing its allele frequecny
Bacterial conjugation is a process where one bacterium transfers genetic material to another through direct contact
What are antibiotics and how do they work?
Antibiotics are chemicals that inhibit the growth of bacteria by interfering with their ability to build cell walls.
How do some bacteria become more resistant to antibiotics?
Due to natural variation from random mutations, some bacteria are more resistant to an antibiotic, giving them a selective advantage.
What has natural selection in bacteria led to?
Natural selection in bacteria has resulted in strains that are antibiotic resistant.
Mechanisms of antibiotic resistance
- inactivation- addition of a phosphate group to the antibiotic, reducing its ability to bind to bacterial ribosomes.
- pumping out-increasing active efflux of the drug, expelling the antibitoic from bacterialcell
- modification- changing the shape of a protein targetted by antibiotic, preventing the drug from binding effectively
4.impermabilty- Impermeability involves a modified cell wall protein that prevents the antibiotic from entering the bacterial cell.
What is the inactivation mechanism of antibiotic resistance?
v Inactivation involves the addition of a phosphate group to the antibiotic, reducing its ability to bind to bacterial ribosomes.
What does the “pumping out” mechanism in antibiotic resistance refer to?
: Pumping out involves increasing the active efflux of the drug, expelling the antibiotic from the bacterial cell.
How does the modification mechanism work in antibiotic resistance?
Modification involves changing the shape of a protein targeted by the antibiotic, preventing the drug from binding effectively.
What does the impermeability mechanism involve in antibiotic resistance?
Impermeability involves a modified cell wall protein that prevents the antibiotic from entering the bacterial cell.
Factors which contribute to formation of antibiotic-resistant bacteria
Inappropriate compliance with treatment plan: course of antibiotics is prematurely stopped. May not eliminate all bacteria, which allows them to continue to replicate and time to accumulate mutations
Inappropriate use of antibiotics: antibiotics prescribed when they are not required. Normal flora is disrupted
Widespread use of antibiotics: increased use of antibiotics can increase the probability of antibiotic-resistant bacteria.
How do viruses adapt and modify their surface antigens?
Viruses constantly adapt and modify their surface antigens through antigenic drift and antigenic shift, which allows them to increase virulence.
Antigenic drift:
involves small and gradual changes to the genes encoding for viral surface antigens. As mutations accumulate, a new subtype of virus can form.
Antigenic shift:
involves sudden and significant changes in the genes encoding for viral surface antigens. Occurs when two or more different strains combine when co-infecting a host resulting in viral recombination.
