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Flashcards in Antimicrobial Chemotherapy Deck (131)
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1

What are antibiotics active against

Only bacteria

2

Define bactericidal

Antimicrobial that kills bacteria
(e.g. penicillins)

3

Define bacteriostatic

Antimicrobial that inhibits growth of bacteria
(e.g. erythromycin)

4

Define sensitive

Organism is sensitive if it is inhibited or killed by the antimicrobial available at the site of infection

5

Define resistant

Organism is resistant if it is not killed or inhibited by the antimicrobial available at the site of infection

6

Define MBC

Minimal bactericidal concentration
Minimum concentration of antimicrobial needed to kill a given organism

7

Define MIC

Minimal inhibitory concentration
Minimum concentration of antimicrobial needed to inhibit growth of a given organism

8

How can antimicrobials be administered

Topically
Systemically
Parenterally

9

What is topical administration

Applied to a surface (skin or to mucous membranes
e.g. conjunctiva)

10

What is systemic administration

Taken internally
(orally or parenterally)

11

What is parenteral administration

Administered intra-venously (iv) or intra-muscularly (im), occassionally subcutaneously

12

What are the three different areas of metabolic activity that antibiotics can use as their mechanism of action

Inhibition of cell wall synthesis (e.g. penicillins & cephalosporins)
Inhibition of nucleic acid synthesis (e.g. trimethoprim & ciprofloxacin)
Inhibition of protein synthesis (e.g. gentamicin & erythromycin)

13

Why can humans use antibiotics which inhibit cell wall synthesis

Humans don't have a cell wall

14

What are penicillins and cephalosporins

β-lactams

15

How do β-lactams work

They disrupt peptidoglycan synthesis by inhibiting the enzymes (penicillin-binding proteins, PBPs)
responsible for cross-linking the carbohydrate chains

16

What types of antibiotics inhibit cell wall synthesis

β-lactams
Glycopeptides

17

What type of cell walls can glycopeptides penetrate

Gram positive

18

How must glycopeptides be administered

Parenterally (except in special circumstances)
as it cannot be absorbed from the GI tract

19

What is the mechanism of action for glycopeptides

They act on cell wall synthesis at a stage prior to β-lactams so inhibit assembly of a peptidoglycan precursor

20

Give examples of glycopeptides

Vancomycin
Teicoplanin

21

How is vancomycin administered to avoid the common toxicity

Careful I.V. infusion to avoid local tissue damage
Important to monitor levels of vancomycin
serum drug concentration is high enough to be therapeutic but not toxic

22

What are the advantages of teicoplanin

Its less toxic than vancomycin and has the advantage of single daily dosing

23

What types of antibiotics inhibit protein synthesis

Aminoglycosides
Macrolides
Tetracyclines
Oxazolidinones
Cyclic Lipopeptide

24

What is protein synthesis

The translation of messenger RNA at the ribosome

The differences between the bacterial ribosome and the mammalian ribosome allow selective action on bacterial protein synthesis

25

What are aminoglycosides useful for

Treatment of serious Gram negative infection (e.g. coliform)

26

Give an example on an aminoglycosides

Gentamicin which is toxic and requires a careful dosing regime and monitoring of levels

27

What are macrolides useful for

Useful as alternatives to penicillins in treatment of gram positive infections in patients who are penicillin allergic

28

Give an example of macrolides

Erythromycin

29

Give an example of oxazolidinones

Linezolid which can be given orally
Tends to be held in reserve for the treatment of serious infection

30

Give an example of a cyclic lipopeptide

Daptomycin has activity against Gram positives in general and MRSA in particular
Used in serious infections on specialist advice