Antibiotics and Vaccines Flashcards
What are cidal agents?
Antibiotics that kill organisms are called cidal agents
These agents are termed bacteriocidal, fungicidal
and viricidal agents, killing bacteria, fungi, and
viruses, respectively
What are static agents?
Antibiotics that do not kill but only inhibit growth are
called static agents,
These include bacteriostatic, fungistatic and
viristatic agents
What does the choice of an antibiotic depend on?
4
on site of infection and the ability of antibiotics to
penetrate that site
Immune response of host
Nature of pathogen
Results of antibiotic susceptibility tests from the
microbiology lab
What does the duration of antibiotic treatment depend on?
The site and the pathogen
What are broad spectrum antibiotics?
Antibiotics that act on both Gram-positive and Gram-
negative bacteria are called broad-spectrum agents-
useful if pathogen not yet identified, but have
disruptive effect on the microbiome
What are narrow spectrum antibiotics?
An antibiotic acting on a single group of organisms-
narrow spectrum agent- preferable when pathogen
has been identified- less effect on microbiome
What are the five main antibiotic targets in bacteria?
Cell wall
Protein synthesis
Nucleic acid synthesis
Cytoplasmic membrane
Essential- metabolic pathway- folic acid synthesis
How do antibiotics attack the cell wall?
3
Agents inhibit the synthesis of the cell wall
Inhibit the cross-linking of the peptidogylcan- results
in a weak cell wall and osmotic lysis of the bacterium
E.g. of cell wall agents are the β-lactam antibiotics
which includes penicillin, ampicillin and methicillin
What type of antibiotics are penicillin and methicilin?
β-lactam antibiotics
What are β-lactam antibiotics?
Broad spectrum antibiotics that attach the synthesis of the cell wall
How do antibiotics target protein synthesis?
Agents that bind irreversibly to bacterial ribosome
and inhibit protein synthesis
Give an example of a type of antibiotic that affects protein synthesis of bacteria.
Aminoglycosides
What are aminoglycosides?
3
Narrow spectrum antibiotics used for gram negative bacilli
They target protein synthesis in bacteria
Prolonged usage causes hearing and kidney damage
How do antibiotics target nucleic acid synthesis?
2
Inhibitors of DNA replication
Prevent supercoiling of bacterial chromosome
Give an example of an antibiotic that targets nucleic acid synthesis.
Fluoroquinolones
What are fluoroquinolones?
2
Antibiotics that target nucleic acid synthesis
Broad spectrum - gram + and - infection
How do antibiotics target cytoplasmic membrane?
Disorganise structure of the cytoplasmic membrane
Give an example of an antibiotic that targets the cytoplasmic membrane.
Amphotericin B (fungal infections)
How do antibiotics target folic acid synthesis?
Inhibit synthesis of folic acid
Give an example of an agent that targets folic acid synthesis.
(2)
• E.g. sulphonamide and trimethoprim-
act in synergy
• Used in combination in the treatment of
urinary tract infection
How does one know the antimicrobial susceptibility of an antibiotic?
(2)
Disc diffusion
Measure the diameter of the zone of inhibition for each antibiotic-
the bigger the zone the more susceptible the isolate
What are vaccines?
A vaccine is a preparation which is used to improve
immunity to a particular infection- prevent infection
