antibiotics

Question 1

Describe cell wall as a target for antibiotics

Answer 1

Good target as cell wall contains components unique to bacteria (peptidoglycans)

Examples:
Penicillin (β-lactam)
Ampicillin (β-lactam)
Vancomycin (glycopeptide)

Β-lactams inhibits transpeptidation by binding to penicillin-binding proteins (PBPs) on maturing peptidoglycan strands
–> decrease in peptidoglycans
Also promotes autolysin activity

Bactericidal

Question 2

Describe cell membrane as a target for antibiotics

Answer 2

Good target as disrupted functional integrity of cell membrane leads to escape macromolecules & ions from bacterial cells

Disadvantages:
High level of similarity between bacterial & animal cell membranes

Examples:
Polymixin, colistin

Target outer membrane of gram negative bacteria

Bactericidal

Question 3

Describe nucleic acid synthesis as a target for antibiotics

Answer 3

Good target as organisation & replication of bacterial DNA & RNA differ to eukaryote

Examples:
Quinolones (nalidixic acid) & Novobiocin
Rifampin

Bacteriostatic

Question 4

Describe protein synthesis as a target for antibiotics

Answer 4

Good target as there are differences in ribosome structure between eukaryotes (80S) & prokaryotes (70S)

Examples:
Tetracycline
Erythromycin & Chloramphenicol
Aminoglycosides

Bacteriostatic

Question 5

Antibiotic resistance mechanisms

Answer 5

Enzymes that degrade or inactivate antibiotic
B-lactamases – penicillin/ampicillin

Alteration of target site
Altered ribosome structure – erythromycin

Elimination of antibiotic from bacterial cell
Efflux pump – tetracycline

Bacterial cell impermeable for antibiotic
Gram negative cell wall – penicillin

Question 6

How does antibiotic use lead to increased antibiotic resistance

Answer 6

selection pressure –> only resistant bacteria survive & replicate –> next generation is highly resistant

Question 7

Importance of microbiology in veterinary science

Answer 7

Understanding disease-causing microorganisms
Developing effective treatments
Preventing spread of infectious diseases
Ensuring food safety
Environmental health
Public health

Question 8

What is the microbial disease process

Answer 8

Exposure
Adhesion
Invasion
Colonisation
Pathogenesis
Immune response
Resolution