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Infection A > Session 4 Lecture 1 > Flashcards

Session 4 Lecture 1 Flashcards

1
Q

What is an antimicrobial?

A

Agent that is active against a microbe

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2
Q

What is an antibiotic?

A

Agent derived from a living organism that acts against a microbe.

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3
Q

What are the different types of antimicrobials?

A

Antibacterial, antifungal, antiviral and antiprotozoal agents.

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4
Q

How are antibacterial agents classified?

A
  • Bactericidal or bacteriostatic
  • Spectrum - broad v narrow
  • Target site
  • Chemical structure
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5
Q

Define bacteriostatic effect

A

an antibiotic can have this effect if it stops the bacteria from reproducing while not necessarily killing the bacteria otherwise

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6
Q

Define bactericidal effect?

A

An antibiotic can have this effect by which they inhibit the growth of the bacteria

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7
Q

What are the ideal features of antimicrobial agents?

A

Selectively toxic, few adverse effects, reach site of infection, oral/IV formulation, long half life and no interference with other drugs

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8
Q

What are the four fundamental mechanisms of action that antibacterials have?

A

Cell wall synthesis, cell membrane function, protein synthesis and nucleic acid synthesis

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9
Q

What type of antibiotic is penicillin?

A

Beta lactate antibiotic

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10
Q

What does penicillin do?

A

Inhibits the formation of peptidoglycan cross links in the bacterial cell wall.

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11
Q

How does penicillin work?

A

Penicillin binds to enzyme DD-transpeptidase hence it can;t catalyse formation of cross links. Weakens the cell wall hence causes cell death.

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12
Q

Why is vancomycin medially important?

A

Because of its effectiveness against multi drug resistance organisms such as MRSA.

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13
Q

What does vancomycin do?

A

Inhibits the synthesis of bacterial cell wall phospholipids as well as peptidoglycan polymerisation at a site earlier than that inhibited by penicillin.

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14
Q

What sort of bacteria does vancomycin work against?

A

gram positive bacteria

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15
Q

What is the difference between penicillin and vancomycin?

A

For penicillin, the peptidoglycan is formed but not cross linked. For vancomycin you don’t form peptidoglycan.

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16
Q

What is a quinolone?

A

Family of synthetic broad-spectrum antibiotic drugs

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17
Q

What are fluoroquinolones?

A

These are the majority of quinolone that are used clinically. They have a fluorine atom attached to the central ring system.

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18
Q

What suffix do most fluoroquinolone have?

A
  • oxacin
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19
Q

What do fluoroquinolones do?

A

Inhibit the replication of bacterial DNA

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20
Q

What are the different types of resistance?

A

Intrinsic, acquired and adaptive

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21
Q

Describe intrinsic resistance

A

No target or access for the drug. Usually permanent

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22
Q

Describe acquired resistance

A

Acquires new genetic material or mutates. Usually permanent

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23
Q

Describe adaptive resistance

A

The organism response to a stress (eg sub-inhibitory level of antibiotic). Usually reversible

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24
Q

What are the different mechanisms of resistance?

A
  • Drug inactivating enzyme
  • Altered target
  • Altered uptake
25
Q

What are the genetic basis of antibiotic resistance?

A
  • Chromosomal gene mutation

- Horizontal gene transfer

26
Q

What are the different types of susceptibility testing?

A
  • Disk sensitivity testing

- Minimal inhibitory concentration

27
Q

What is Dias sensitivity testing?

A

Place exact amounts of antimicrobial agents on culture dishes and inoculate with the microorganism.

28
Q

What does the organisms growth on a disk sensitivity test show?

A

Its resistance to the drug

29
Q

What type of method is the disk sensitive method?

A

Qualititative

30
Q

What type of method is minimal inhibitory concentration method?

A

Quantitative method

31
Q

What is the minimal inhibitory concentration?

A

The minimum concentration of the antibiotic necessary to prevent bacterial growth.

32
Q

What is the minimal inhibitory concentration method?

A

Dilution technique where tubes containing serial dilutions of an antibiotic are inoculated with the organism.

33
Q

What are the different types of beta lactams?

A

Penicillin, cephalosporins, carbapenems and monobactams.

34
Q

Give some examples of penicillins

A

Penicillin, amoxicillin, flucloxacillin

35
Q

Describe some features of cephalosporins

A
  • High broad spectrum
  • Effective against gram neg and gram pos
  • No anaerobic activity
36
Q

Give an example of a cephalosporin

A

Cetriaxone - good activity in the CSF

37
Q

Describe some features of carbapenems

A
  • Very broad spectrum (inc anaerobes)
  • Active against most (not all) gram negs
  • Generally safe in penicillin allergy
38
Q

Give some example of carbapenems

A

Meropenem

39
Q

Give some examples of glycopeptide antibiotics

A

Vancomycin, teicoplanin

40
Q

Describe some features of teicoplanin

A

Similar activity to vancomycin but easier to administer

41
Q

Describe some features of vancomycin

A 
Active against most gram pos
Not absorbed (oral for C.diff only)
42
Q

Describe some features of tetracyclines

A
  • Similar spectrum, oral only

- Broad spectrum but specific use in penicillin allergy, usually for gram pos

43
Q

Give some examples of tetracyclines

A

Tetracycline and doxycycline

44
Q

Give some examples of aminoglycoside

A

Most common agent is gentamicin

45
Q

Describe some features of aminoglycosides

A
  • Profound activity against gram neg
  • Good activity in blood and urine
  • Generally reserved for severe gram neg sepsis
46
Q

Give some examples of macrolides

A

Erythromycin and clarithromycin

47
Q

Describe some features of macrolides

A
  • Well distributed including intracellular penetration

- Alternative to penicillin for mild gram pos infections

48
Q

Give an example of a quinolone

A

Cciprofloxacin

49
Q

Describe some features of quinolone

A

Inhibit DNA gyrase
Very active against gram neg
Increasing resistance and risk of c diff

50
Q

What is trimethoprim used for

A

UTI

51
Q

What is the action of trimethoprim and sulphonamides?

A

Inhibited of folic acid synthesis

52
Q

When trimethoprim and sulphonamides are combined with sulphamethoxazole what are the features?

A

Used to treat PCP and has activity against MRSA

53
Q

Give examples of antifungal drugs

A

Azoles

Polyenes

54
Q

What do azoles do?

A

Inhibit cell membrane synthesis

55
Q

What is fluconazole used to treat?

A

Candida

56
Q

What do polyenes do?

A

INhibit cell membrane function

57
Q

Give some examples of antivirals

A

Aciclovoir

Oseltamivir

58
Q

What does aciclovir do?

A

When phosphorylates inhibits viral DNA polymerase

Infection A (18 decks)

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