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All you need to know and more > Antimicrobial Chemotherapy 1 COPY > Flashcards

Antimicrobial Chemotherapy 1 COPY Flashcards

1
Q

Define ‘bactericidal’

A

An antimicrobial that kills bacteria (eg the penicillins)

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2
Q

Define bacteriostatic

A

An antimicrobial that inhibits growth of bacteria (eg. erythromycin)

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3
Q

Define ‘sensitive’

A

An organism is considered sensitive if it inhibited or killed by levels of the antimicrobial that are available at the site of infection

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4
Q

Define ‘resistant’

A

An organism is considered resistant if it is not killed or inhibited by levels of the antimicrobial that are available at the site of infection

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5
Q

Define ‘MIC’

A

Minimal inhibitory concentration - The minimum conc. of an antimicrobial needed to inhibit visible growth of a given organism

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6
Q

Define ‘MBC’

A

Minimal bactericidal conc. - The minimum conc. of the antimicrobial needed to kill a given organism

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7
Q

What are the 3 routes of administration

A

Systemic - taken internally, either orally or parenterallyTopical

  • Applied to the surface, usually skin or to mucous membranes e.g. conjunctiva Parenteral
  • Administered either intra-venously (iv) or intra-muscularly (im), occasionally subcutaneously
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8
Q

What are the 3 mechanisms of action of antimicrobial agents

A

Inhibition of cell wall synthesis

Inhibition of protein synthesis

Inhibition of nucleic acid synthesis

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9
Q

what two types of drugs are β-lactams

A

Penicillins and cephalosporins β-lactam antibiotics disrupt peptidoglycan synthesisby inhibiting the enzymes which are responsible for cross

-l inking the carbohydrate chains.(Peptidoglycan is an important structural component of the bacterial cell wall and the enzymesinvolved in its synthesis_

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10
Q

What are the two types of antimicrobials which inhibit cell wall synthesis

A

Glycopeptides and β-lactams

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11
Q

What are two common glycopeptides

A

Vancomycin and teicoplanin

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12
Q

Describe the mechanism and range of action of glycopeptides

A

They inhibit cell wall synthesis - but at a prior stage than B-lactamsthey act only on gram positive organisms

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13
Q

What route of administration must glycopeptides take (unless special circumstances)

A

Parenterally

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14
Q

What is one side effect of vancomycin

A

It is toxic

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15
Q

What are the 4 types of antimicrobial which inhibit protein syntehsis

A
  • Aminoglycosides
  • Macrolides and tetracyclines
  • Oxazolidinones
  • Cyclic lipopeptides
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16
Q

What type of bacteria are aninoglycosides useful for?

A

Serious gram negative Infection

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17
Q

What type of drug is getamicin and what is a common side effect of adminsitration

A

It is an Aminoglycoside and is toxic

  • requiring a careful dosing regime and motoring of levels
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18
Q

What are the uses of macrolides and tatracyclines

A

Useful in treatment of gram positive infections in patients who are penicillin allergic

  • however CANNOT BE USED WITHOUT LABORATORY TESTING
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19
Q

What class of drug is linezolid and what is it commonly used for?

A

It is an oxazolidonones (protein synthesis inhibitor). It has good activity against MRSA

  • Typically held in reserve for the treatment of serious infection
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20
Q

What class of drug is daptomycin and what it is commonly used for?

A

Cylic lipopeptide (protein synthesis inhibitor). Activity against gram positives in general and MRSA in particular

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21
Q

What are the 2 classes of drug which inhibit nucleic acid synthesis

A
  • Trimethoprim and sulphamethoxazole

- Fluoroquinolone’s

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22
Q

What type of drug is ciprofloxacin? What it is commonly used for? What are some of the drawbacks of the

A

Ciprofloxacin is a fluoroquinolone (nucleic acid inhibitor).

commonly used against gram negative organisms.

Can be taken orally

Not to be used in children

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23
Q

Describe inherent or intrinsic resistance

A

In some cases all strains of a given species are naturally resistant to an antibiotic.

This is usually due to inability of drug to penetrate the bacterial cell wall to exert its action

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24
Q

What are the 2 ways in which acquired resistance may be acquired?

A
  1. A spontaneous mutation during multiplication or bacterial DNA can result in a change in structure or function which no longer allows the antibiotic to act as its target may have changed
  2. The gene or genes that code for resistance can spread from organism to organism or indeed from species to species. This is by far the most common mode of the spread of resistance and genes can be carried on by plasmids (extra chromosomal packages for DNA) or on transposons (packets of DNA which insert themselves into the chromosome
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25
Q

What are the 2 mechanisms of resistance to β–lactam antibiotics?

A

β-lactamase production - β-lactamases are bacterial enzymes which cleave the β–lactam ring of the antibiotic and thusrender it inactiveAlteration of penicillin binding protein (PBP) target site

  • Mutations in PBP genes result in amodified target site to which β–lactams will no longer bind
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26
Q

What drug is β-lactamase resistant

A

Flucloxacillin ( and hence can be used to treat β-lactamase producing staph. aureus

27
Q

What are ESBL’s and what are the implications of their existence

A

Extended spectrum β–lactamases (ESBLs) are an increasing problem in hospitals and are producedby some Gram negative organisms.

These β–lactamases can break down third generationcephalosporins as well as penicillins and therefore render the organism resistant to all β–lactamantibiotics

28
Q

What glycopeptide resistant bacteria has appeared recently and what are the implications of this mutation?

A

Vancomycin resistant enterococci (VREs) have appeared recently.
The major concern among microbiologists isthat this mechanism of resistance might spread from enterococci to Staph aureus, producingvancomycin resistant Staph aureus.

Staph aureus is a more significant pathogen than enterococciand this prospect is viewed with alarm

29
Q

Describe the spectrum of Benzyl penicillin (penicillin G)

A

Best choice for intra-venous treatment of serious pneumococcal, meningococcal and step pyogens

30
Q

Describe the spectrum of amoxicillin/ampicillin

A

Effective against streptococci and coliforms

31
Q

Describe the spectrum of co-amoxiclov

A

Effective against B-lactamase producing coliforms

32
Q

Describe the spectrum of flucloxacillin

A

Effective against staph infections

33
Q

Describe the spectrum of peperacillin

A

Effective against Enterococcus faecalis and pseudomonas species

34
Q

Describe the spectrum of cephalosporins

A

Activity against Gram -‘ve organisms increases from 1st through 3rd generation

Activity against Gram +’ve organisms decreases from 1st through 3rd generation

Generally not used as much anymore as they seem to encourage Ciff D infections

35
Q

How must cephalosporins be taken?

A

Parenteral use only

36
Q

Describe the specrum of aminoglycocides

A

Noted for action against Gram -‘ve organisms

Effective against staphlococci but not streptococci

Gentamicin cheapest and most common aminoglycocide

37
Q

Describe the spectrum of glycopeptides

A

Only gram +’ve organisms are affected (anaerobic +aerobic)

Vancomycin most common example

38
Q

Describe the spectrum of action of macrolides

A

Mainly used against gram +’ve organisms

  • Used as an alternative to penicillin for patients with a penicillin allergy
39
Q

Describe the spectrum of action of Quinolones

A

Nearly all gram -‘ve organisms are sensitive

Mainly used in treatment of community acquired pneumonia

40
Q

Describe the spectrum of action of metronidazole

A

Effective against Gram +’ve and -‘ve anaerobes

41
Q

Describe the spectrum of action of fusidic acid

A

Only used as staphylococcal drug

42
Q

Describe the spectrum of action of trimethoprim

A

Used in urinary infections

43
Q

Describe the spectrum of action of tetracyclines

A

Used in genital tract and urinary tract infections

44
Q

Describe the spectrum of action of clindamycin

A

Effective against Gram +’ve organisms

45
Q

What infection is linezolid used against

A

MRSA

46
Q

What infection is fidoxmicin used against

A

C. diff

47
Q

What infection is daptomycin used against?

A

MRSA

48
Q

What are the 4 classes of anti-fungal drugs?

A

Polyenes

Echinocandins

Allymines

Azoles

49
Q

Describe the mechanism of polyenes

A

They bind to the ergosterol which is present in the fungal cell wall but not in the bacterial cell wall resulting increased permeability of the cell wall.

HOWEVER this also binds to mammalian sterols making polyenes TOXIC

50
Q

Describe the use of amphotericin B and Nystatin (Hint: they are Polyenes)

A

Amphotericin B is used intra-venously for serious yeast infections and other fungal infections.

Very toxic.

Nystatin is used topically or in oral suspension and is not an intra-venous agent for serious fungal infection

51
Q

Describe the mechanism of Azoles

A

Inhibit ergesterol synthesis

52
Q

What is fluconazole used to treat?

A

Yeast infections

53
Q

What are voriconazole and intraconazole used to treat?

A

Aspergillosis

54
Q

Describe the mechanism of allylamines

A

They suppress the ergosterol synthesis but act at a different stage of the synthetic pathway from azoles

55
Q

Describe the use of Terbinafine

A

Used for fungal infections of the skin and nails

56
Q

Describe the mechanism of echinocandinds

A

They inhibit the synthesis of glucan polysaccharide in several types of fungi

57
Q

What are echinocandins used for?

A

Serious candida and aspergillus infections

58
Q

Describe anti-herpes virus drugs

A

All become latent and include: Herpes simplex virus (HSV), eptein-barr virus (HBV), cytomegalovirus (CMV) and Varicella-Zoster Virus (VZV).

59
Q

Describe the mechanism and function of Aciclovir

A

Nucleotide anologue. Converted into active form by an enzyme. It is specific for virus

  • infected cells meaning it is not very toxicExtremely active againstHSV and active against VZVIV used for serious, Oral for less serious
60
Q

Describe the use of valaciclovir and famciclovir

A

Related to aviclovir

- Used in oral treatment of HSV and shingles

61
Q

Describe the use of valganciclovir

A

Pro drug of ganciclovir -> alternative treatment for CMV.

High levels of bone marrow toxicity

62
Q

Describe the use of foscarnet

A

Used for HSV, VSV and CMVHighly nephrotoxic

63
Q

Describe the use of Cidofovir

A

Used for CMV retinitis

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