Antimicrobial Chemotherapy Flashcards

1
Q

Bactericidal

A

kills bacteria

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2
Q

Bacteriostatic

A

will inhibit growth of bacteria

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3
Q

MIC

A

minimum inhibitory concentration

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4
Q

MBC

A

minimum bactericidal concentration

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5
Q

Topical administration

A

applied to a surface e.g. skin or mucous membranes

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6
Q

Systemic administration

A

taken internally either orally or parenterally

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7
Q

Parenteral administration

A

IV or intramuscularly

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8
Q

What 3 sites do antibiotics act on?

A

cell wall synthesis
protein synthesis
nucleic acid synthesis

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9
Q

Cell wall synthesis inhibitors

A

……

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10
Q

Name 2 drugs that will inhibit cell wall synthesis.

A

penicillins
cephalosporins
(beta lactams)

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11
Q

How do beta lactams inhibit cell wall synthesis?

A

inhibit enzymes that cause the cross linking of the peptidoglycan chains

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12
Q

What penicillin is effective against enterococcus faecalis and pseudomonas species and some anaerobes?

A

piperacillin

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13
Q

Name 2 carbapenem family (related to penicillins) drugs that have the widest spectrum of all and are effective against nearly all bacteria, including anaerobes?

A

meropenem and imipenem

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14
Q

How is the activity of cephalosporins against gram negative organisms affected as the generation number increases?

A

the activity increases

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15
Q

How does cephalosporin activity against gram positive organisms change as generation number increases?

A

the activity decreases

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16
Q

What is the name of another class of antibiotics that inhibit cell wall synthesis?

A

glycopeptides

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17
Q

How do glycopeptides inhibit cell wall synthesis?

A

They inhibit the formation of a peptidoglycan precursor.

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18
Q

Give examples of glycopeptide antibiotics.

A

vancomycin and teicoplanin

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19
Q

How are glycopeptides administered?

A

parenterally

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20
Q

Give a limitation of glycopeptide antibiotics.

A

can only act on gram positive infection as cannot penetrate gram negative cell wall

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21
Q

What is a common problem with vancomycin?

A

toxicity

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22
Q

What drug would be used to treat a serious MRSA infection?

A

intravenous vancomycin

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23
Q

What is ampicillin?

A

a broad spectrum penicillin

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24
Q

Inhibition of Protein Synthesis

A

….

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25
Q

There are 4 groups of protein synthesis inhibiting antibiotics. Name them.

A

aminoglycosides
oxazolidinones
cyclic lipopeptides
macrolides and tetracyclines

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26
Q

Give an example of an aminoglycoside, how it is administered and state an issue with it.

A

gentamicin
parenterally
toxic

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27
Q

What type of bacteria are aminoglycosides particularly useful in treating?

A

serious gram negative infections including pseudomonas

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28
Q

What are important side effects of aminoglycosides?

A

nephrotoxicity

otoxicity (to the ear)

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29
Q

Macrolides and Tetracyclines.

Give 2 examples of macrolides and what they are used for.

A

clarithromycin
erythromycin
used in penicillin allergic patients to treat gram positive infection

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30
Q

What conditions are macrocodes also commonly used to treat?

A

early stage syphillis

uncomplicated genital chlamydia infection

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31
Q

What macrolide drug is effective for single dose treatment of chlamydia infection?

A

azithromycin

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32
Q

10% of which types of bacteria are macrolide resistant?

A

streptococcus pyogenes
staphylococcus aureus
streptococcus pneumoniae

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33
Q

Give an example of an oxazolidinone.

How is it administered? What is it effective against? When is it used?

A

linezolid
administered orally
effective against MRSA
held in reserve for use in serious infection

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34
Q

Give an example of a cyclic lipopetide. What is it used against? When is it used?

A

daptomycin
gram positive bacteria, particularly MRSA
held in reserve for use on specialist advice

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35
Q

Inhibitors of Nucleic Acid Synthesis

A

….

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36
Q

Name the two classes of nucleic acid inhibiting antibiotics.

A

trimethoprim and suxamethoxazole

fluoroquinolones

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37
Q

What do trimethoprim and suxamethoxazole do?

A

Trimethoprim on its own can be used to treat UTI
A combined drug of trimethoprim and suxamethoxazole called co-trimoxazole is used it the treatment of respiratory tract infections as it is less likely to cause C.diff infection.

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38
Q

Give an example of a fluoroquinolone, what it does and what it is effective against.

A

ciprofloxacin
inhibits DNA synthesis more directly
effective against gram negative organisms

39
Q

Which group cannot be prescribed ciprofloxacin and why?

A

children

danger of interference with cartilage growth

40
Q

What range of bacteria are quinolone effective against?

A

nearly all gram negative infections inculding pseudomonas

41
Q

Antibiotic Resistance

A

….

42
Q

Beta lactam resistance is characterised by 2 mechanisms. What are they?

A
  1. produce beta lactamase which can cleave the beta lactam loop which is the active component in penicillins and cephalosporins e.g staph. aureus
  2. have an altered penicillin binding site, therefore drugs can no longer bind to the organisms to have an effect e.g MRSA
43
Q

What beta lactam antibiotic can be used to overcome organisms such as s.aureus that can produce beta lactamase?

A

flucloxacillin - is beta lactamase resistant

44
Q

What drugs is MRSA resistant to?

A

all beta lactams

45
Q

What are ESBLs? (extended spectrum beta-lactamases)

A

chemicals produced by some gram negative organisms rendering them resistant to beta lactam agents

46
Q

How is glycopeptide resistance characterised?

A

the peptidoglycan precursor to which vancomycin normally binds has an altered structure therefore cannot bind

47
Q

How common is vancomycin resistance in gram positive bacteria?

A

very rare, however vancomycin resistant enterococci have appeared recently

48
Q

What is the concern with vancomycin resistant enterococci?

A

that they will pass their mechanism of resistance on to s.aureus

49
Q

Describe one other antibiotic resistance mechanism.

A

blocking transport of drug into cell or actively pumping it out

50
Q

What drug could you give to treat a serious infection with a gram negative organism such as E.coli?

A

IV Gentamicin

51
Q

Antifungal Drugs

A

….

52
Q

What 2 groups can fungi be divided into?

A
filamentous fungi (moulds)
yeasts
53
Q

Name the different classes of anti fungal drugs.

A

azoles
polyenes
allylamines
echinocandins

54
Q

What fungi are polyenes effective against?

A

both yeasts and filamentous fungi

55
Q

How do polyenes combat fungi?

A

by binding to ergosterol which is present in the fungal cell wall

56
Q

What is amphotericin B used for and how is it administered?

A

serious fungal infection

intravenously

57
Q

What is an issue with amphotericin B?

A

it is toxic

58
Q

What polyene drug is used topically and in oral suspension?

A

nystatin

59
Q

Give examples of when nystatin would be used clinically.

A

creams for skin fungal infections

pessaries for vaginal candida infections

60
Q

What do azoles do?

A

inhibit ergosterol synthesis

61
Q

What azole drug is used to treat yeast infection but not filamentous fungi infection?

A

fluconazole

62
Q

What two azole drugs can treat Aspergillosis?

A

voriconazole and itraconazole (VAI)

63
Q

What do allylamines do?

A

inhibit ergosterol synthesis at a different stage to the azoles

64
Q

What is the name of the only allylamine in common clinical use?

A

terbinafine

65
Q

What is terbinafine used to treat?

A

mainly dermatophytes (ringworm infections and athletes foot)

66
Q

What do echinocandins do?

A

inhibit synthesis of glucan polysaccharide in several types of fungi

67
Q

When are echinocandins used?

A

for serious aspergillus and candida infections

68
Q

Anti-Viral Drugs

A

69
Q

What are 4 main herpes viruses?

A

herpes simplex virus
epstein-barr virus
varicella zoster virus
cytomegalovirus

70
Q

What is an important feature of all herpes family viruses?

A

they become latent

71
Q

Name a drug that is effective against HSV and VSV.

A

aciclovir - oral

72
Q

How does aciclovir work?

A

It is a nucleoside analogue that will become active by an enzyme coded for by the virus genome

73
Q

How can aciclovir be administered?

A

IV - serious infections such as VZV pneumonitis
orally-cold sores
topically - cold sores

74
Q

Name a drug involved in HIV therapy.

A

saquinavir

75
Q

What is the name of the first drug treatment for HIV and how did it work?

A

zidovudine

nucleoside analogue that interfered with the action of reverse transcriptase

76
Q

What is now common practice in the treatment of HIV?

A

using a combination of 3 drugs active at different stages of DNA replication

77
Q

How do we monitor a patient’s response to anti-HIV drugs?

A

viral load

CD4+ cell count

78
Q

What is a problem with the anti-HIV drugs?

A

toxic

79
Q

What protein produced naturally by the immune system but made available clinically by genetic engineering is used to treat selective hepatitis B and C infections?

A

interferon alpha

80
Q

What factors have limited the use of interferon alpha as a treatment for Hep B and C?

A

ineffective on its own
serious side effects
expensive

81
Q

What drug, mainly used for HIV treatment, is also used for treatment of Hep B?

A

lamivudine - given orally

82
Q

What is a common treatment for hepatitis C?

A

combination therapy of ribavarin and interferon alpha

83
Q

Name 2 common viral respiratory infections.

A

Influenza A

Influenza B

84
Q

What 2 drugs are licensed to treat Influenzas A and B within 48 hours of onset of symptoms?

A

zanamavir and oseltamavir (ZOI)

85
Q

UTI Agents

A

86
Q

What 2 drugs are used in the treatment of lower urinary tract infections?

A

nalidixic acid - only gram negative aerobes

nitrofurantoin - gram negative and some gram positive

87
Q

What group of drugs are allergic reactions most often associated with?

A

beta lactams

88
Q

What is an important side effect of antibiotic therapy?

A

C.diff infection

89
Q

What is C.diff infection treated with?

A

oral metronidazole or oral vancomycin

90
Q

Use of what group is most commonly related to renal toxicity?

A

aminoglycosides

91
Q

When antimicrobials are used in combination there are 3 possible outcomes. What are they?

A
  1. effects are additive
  2. effects are antagonistic
  3. effects are synergistic
92
Q

What is the general outcome of two cidal drugs or 2 static drugs?

A

additive or synergistic

93
Q

What is the general outcome of combining one tidal and one static drug?

A

antagonism

94
Q

What is an ‘E-test’?

A

a way to measure MIC of one antibiotic against another. It is a paper strip test.