Antibiotics Flashcards Preview

UofG Medicine Question Bank 2020 > Antibiotics > Flashcards

Flashcards in Antibiotics Deck (30)
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1
Q

What are the types of prescribing used in antibiotics?

A

Guided, Empirical, Prophylactic

2
Q

What is guided antibiotic prescribing?

A

Testing to determine the infectious agent, then treating with the most appropriate antibiotic

3
Q

What is empirical antibiotic prescribing?

A

Treating with antibiotics regardless of knowing the type of infection.
Used when leaving the patient would cause more harm than using the wrong antibiotic, i.e. in sepsis or meningitis.

4
Q

What is prophylactic antibiotic prescribing?

A

Prescribing antibiotics to prevent infection.

Used in severely immunocompromised (HIM, Splenectomy, transplantation), post-surgery, animal bites, exposure, insult

5
Q

What are the ideal characteristics of antibiotics?

A

Target Effects- toxic to bacterium, penetrate body area infected, limit bacterial-toxin release, easily administered
Co-lateral Damage- Non-toxic to patient, limits effect on colonizing bacteria (mucosal candida, clostridium difficile, selection of resistant bacteria), low ability of bacteria to escape treatment by developing resistance.

6
Q

What is the name of the antibiotics which treat specific infections?

A

Narrow spectrum agent, used typically for guided therapy

7
Q

What is the name of the antibiotics which treat a variety infections?

A

Broad spectrum, typically used in empirical treatment therapy

8
Q

What is an example of guided antibiotic therapy with positive, mid-stream urine test for E. coli?

A

Nitrofurantoin

  • narrow spectrum
  • penetrates only into urine, minimizing systemic exposure
  • high cure rate
9
Q

What is an example of empirical antibiotic treatment with a positive pneumonia test?

A

Need to treat most common causes of pneumonia (strep. pneumoniae, staph. aureus, legionella pneumophilia, mycoplasma pneumoniae, haemophilus influenza).
Broad spectrum antibiotics, with combination therapy, to cover for different possibilities.
-Co-amoxiclav
- Clarithromycin
After testing, switch to best most narrow treatment

10
Q

What are the types of antibiotic actions?

A

Bactericidal and bacteriostatic

11
Q

What do bactericidal antibiotics do?

A

Stops bacterial growth and also kills the bacteria, achieving sterilization

  • can lead to release of toxins and cause inflammation (typically given anti-inflammatorys alongside)
    i. e. penicillin
12
Q

What do bacteriostatic antibiotics do?

A

Inhibit bacterial growth but don’t kill and sterilize the bacterium.
-require secondary means to clear bacteria

13
Q

What is are important targets in antibiotics?

A

Cell wall, particularly peptidoglycan
Anti-metabolites
Ribosome
DNA / transcription process

14
Q

What do the beta-lactam antibiotics have in common?

A

Presence of beta-lactam ring within its molecule

15
Q

What are important features of penicillin?

A

Rapid bacterial killing with low toxicity,

bactericidal

16
Q

What is the mechanism of action of penicillin?

A

Penicillin is an analogue of the D-ala-D-ala of the cell wall, and can mimic and place self into the wall to prevent the polymerization, and cause lysis
Broad Spectrum

17
Q

What is a major problem with penicillin?

A

Type 1 hypersensitivity mediated by IgE binding to the surface of mast cells, resulting in degranulation and inflammation. More common is sub-acute Type 2 hypersensitivity with IgG inducing complement (hours-days)
1% of patients have immune mediated reaction.
10% claim to have an allergy.

18
Q

What is the mechanism of action for Vancomycin?

A

Similar to penicillin, acts against peptidoglycan cell wall, however very large and therefore cant insert into gram-negative bacteria.

19
Q

What is the most commonly prescribed antibiotic?

A

beta-lactam antibiotics

20
Q

What is the mechanism of action for Clarithromycin and Doxycycline?

A

Target ribosome, switching off protein production
Bacteriostatic
Broad spectrum, act on both gram +/-
Resistance is a problem

21
Q

What is the mechanism of action for Ciprofloxacin?

A

Fluoroquinolones
Targets DNA replication leading to cell death
Broad spectrum
Can target most bacteria effectively
Resistance increasing and becoming big problem

22
Q

What is the mechanism of action for Trimethoprim?

A

Anti-metabolite that inhibits folate metabolism, making bacteria unable to produce basic units needed for DNA
Bacteriostatic
Typically used in UTI

23
Q

How is antibiotic resistance tested?

A

Disc diffusion sensitivity testing
You get zone of clearance in lawn of bacteria if the bacteria is sensitive, they will grow close if resistance is present

24
Q

How does antibiotic resistance occur?

A

Mutation/modification of target site
Inactivating enzymes produced by bacterium that lyse or alter the antibiotics so it isn’t effective
Limit access by reduced permeability so antibiotic cant get inside, or pump it out so the concentration inside is never high enough to work

25
Q

How is resistance carried and passed in bacteria?

A

Passed on plasmids of bacteria

Can be passed vertically between bacteria

26
Q

What is the New Delhi metallo-beta-lactamase 1?

A

Contains plasmids which are able to induce resistance to antibiotics, particularly the beta-lactam group of antibiotics.
Has other plasmids with resistance to quinolone, tetracycline, and many more antibiotics.
Contains beta-lactamase which cannot be inhibited in any way.

27
Q

What do beta-lactamases do?

A

Cut a whole which removes the beta-lactam ring of penicillin, once the ring is cut the penicillin becomes inactive

28
Q

How can we address beta-lactamase and prevent its resistance?

A

Can create antibiotic penicillin’s (flucloxacillin) which can resist the action of the beta-lactamase activity.
Can inhibit the the beta-lactamases using other beta-lactamase stable drugs (clavulanic acid), in conjunction with a beta-lactam antibiotic, therefore protecting the antibiotic

29
Q

What type of bacteria is typically more resisitant?

A

Pan-resistant gram negative strains

30
Q

What is the mechanism of action for Ampicillin?

A

Irreversibly inhibits transpeptidase enzyme which helps build bacterial cell wall.
Bactericidal