S9) Antimicrobial Agents Flashcards Preview

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Flashcards in S9) Antimicrobial Agents Deck (24)
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1
Q

What is an antibacterial drug?

A

An antibacterial drug is a chemical substance that kills or inhibits the growth of bacteria at a discrete target site

2
Q

What is an antibiotic?

A

An antibiotic is an antibacterial drug of microbial origin e.g. penicillin from Penicillium mold

3
Q

What is the unique property of antimicrobials?

A

Antimicrobials target microbial biochemistry

4
Q

Identify some antibiotics which target DNA synthesis

A
  • Quinolones e.g. ciprofloxacin
  • Folic acid antagonists e.g. trimethoprim sulphonamides
5
Q

Identify some antibiotics which target protein synthesis

A
  • Aminoglycosides e.g. gentamicin
  • Macrolides e.g. erythromicin
  • Tetracyclines
6
Q

Identify some antibiotics which target cell wall synthesis

A
  • Beta-lactams e.g. penicillins, cephalosporins, carbapenems
  • Glycopeptides e.g. vancomycin
7
Q

What are the two reasons for antibiotics?

A
  • Prevention of infections
  • Therapy of significant bacterial infections
8
Q

Identify some groups of people at increased risk of infection

A
  • Peri-operative – prevention of surgical site infections
  • Short term – meningitis contacts
  • Long term – asplenia, immunodeficiency
9
Q

What are clinically significant infections?

A

Clinically significant infections are infections that if left untreated will cause death, permanent harm or medium to long term disability

10
Q

What are the two ways in which one can treat a clinically significant infection?

A
  • Treatment of culture-proven infection
  • Empirical treatment of suspected infection
11
Q

What are the two different ways that one might use antibiotics empirically?

A
12
Q

Which factors helps one determine the likely cause of an infection?

A
13
Q

Which factors helps one determine which antibiotics are likely to be effective?

A
14
Q

Which factors helps one determine which antibiotic is the best choice?

A
15
Q

What are the adverse events of antibiotics?

A
  • Toxicities
  • Allergic reactions
  • Idiosyncratic reactions
  • Ecological effects – C.difficile, selection of resistance
  • Drug interactions
16
Q

What would ideal antibiotic therapy look like?

A
  • Clean kill of infecting bacteria – minimal impact on commensal organisms, no resistance in any surviving pathogens
  • No unwanted effects in patient e.g. drug interactions, toxicities
17
Q

Illustrate how one measures the susceptibility of bacteria to antibacterials

A
18
Q

What is the minimum inhibitory concentration?

A

MIC is the minimum concentration of antibiotic required to inhibit growth of a bacterium in vitro (mg/l)

19
Q

Therapeutic drug monitoring is used to ensure a non-toxic adequate dose for some antibiotics.

Identify these

A
  • Aminoglycosides
  • Glycopeptides
20
Q

Describe the mechanism of antibiotic resistance through the following pathways:

  • Antibiotic inactivation
  • Alteration of target site
  • Alteration of metabolic pathways
  • Reduced intracellular antibiotic accumulation
A
21
Q

What does it mean when a pathogen is multi-drug resistant?

A

Multi-drug resistant – non-susceptibility to at least one agent in three or more antimicrobial categories

22
Q

What does it mean when a pathogen is extensively drug resistant?

A

Extensively drug resistant – on-susceptibility to at least one agent in all but two or fewer antimicrobial categories

23
Q

What does it mean when a pathogen is pan drug resistant?

A

Pan drug resistant – non-susceptibility to all agents in al antimicrobial categories

24
Q

Identify the two ways in which bacteria can become resistant to carbapenem

A
  • Reduced bacterial intracellular concentration
  • Carbapenemase production