Antimicrobials Flashcards Preview

[ ESA 3- Infection and Immunity > Antimicrobials > Flashcards

Flashcards in Antimicrobials Deck (120):
1

What can antimicrobials be classified into?

Antibacterials
Antifungals
Antivirals
Antiprotozoals

2

How can antibacterials be classified?

Bactericidal or bacteriostatic
Broad or narrow
Target site
Chemical structure

3

What do bactericidal antibacterials do?

Kill bacteria

4

What do bacteriostatic antibacterials do?

Mainly inhibit

5

What does the target site of an antibacterial depend on?

The mechanism of action

6

What are the ideal features of an antimicrobial agent?

Selectively toxic
Few adverse effects
Reach site of infection
Oral and IV formulation
Long-half life
No interference with other drugs

7

Why should an antimicrobial be selectively toxic?

So it is minimally toxic

8

Why should an antimicrobial have a long half life?

Allows for infrequent dosing

9

What are the classes of mechanism of action of antibacterials?

Affect cell wall synthesis
Affect protein synthesis
Affect cell membrane function
Affect nucleic acid synthesis

10

Give two examples of classes of antimicrobials that affect cell wall synthesis

Beta-lactams
Glycopeptides

11

Give three examples of classes of antimicrobials that affect protein synthesis

Tetracyclines
Aminoglycosides
Macrolides

12

Give an example of a class of antimicrobial that affects cell membrane function?

Polymixins

13

Give an example of a polymixin

Colistin

14

Give an example of a class of antimicrobial that affects nucleic acid synthesis

Quinolones

15

Give two examples of quinolones

Trimethoprim
Rifampicin

16

What are the most important classes of antibacterials?

Those that affect cell wall synthesis and those that interfere with protein synthesis

17

What class of antibacterial is penicillin?

Beta-lactam

18

What is penicillin binding protein?

A bacterial protein that physiologically cross-links the cell walls in bacteria

19

What is the mechanism of action of penicillin?

It binds to penicillin binding protein and inhibits it from cross-link the cell wall

20

What class of antimicrobial is vancomycin?

Glycopeptide

21

What is the mechanism of action of vancomycin?

It sits on the cross-links of the forming cell wall and stops penicillin binding protein from attaching, preventing cross-links from being attached to each other by the cell wall cross-linking enzyme

22

What class of antimicrobial are fluoroquinolones?

Quinolone

23

What is the mechanism of action of fluoroquinolones?

Interferes with the action of DNA gyrase during bacterial growth

24

What does DNA gyrase do?

Physiologically catalyses the supercoiling of DNA

25

How do fluoroquinolones interfere with the action of DNA gyrase?

Binds to both the enzyme and DNA to form a ternary (three molecule) complex, inhibiting the rejoining step and thus causes cell death

26

What are the mechanisms of antimicrobial resistance?

Drug inactivating enzymes
Altered target
Altered uptake

27

Give two examples of antimicrobials affected by drug inactivating enzymes

Beta-lactamases
Aminoglycosides

28

What happens in the altered target mechanism of antimicrobial resistance?

Target enzyme has a lowered affinity for antibacterial

29

Give three examples of antimicrobials affected by the altered target mechanism of resistance

Methicillin
Macrolides
Trimethoprim

30

What is caused by antibiotic resistance to methicillin?

MRSA

31

How can altered uptake be achieved in antibiotic resistance?

Decreased permeability
Increased efflux

32

Give an example of an antimicrobial affected by the decreased permeability mechanism of resistance

Beta-lactams

33

Give an example of an antimicrobial affected by the increased efflux mechanism of resistance

Tetracyclines

34

How can antibiotic resistance be genetically obtained?

Chromosomal gene mutation
Horizontal gene transfer

35

How does a chromosomal gene mutation result in antimicrobial resistance?

A chromosome mutates to contain a gene that confers resistance.
An antibiotic is then applied and the resistant gene is selected for, as only the resistant bacteria will survive.
The surviving bacteria can then replicate to produce large numbers of bacteria the now carry the mutated resistance gene

36

What can antibiotic resistance genes be carried on?

Chromosomes
Plasmids
Transposons

37

How can antibiotic resistance genes be transferred?

Conjugation
Transduction
Transformation

38

How does antimicrobial resistance transfer by conjugation?

Resistant cell carries the gene on a plasmid or transposon that passes it on to another cell via pili

39

How does antimicrobial resistance transfer by transduction?

Resistant cell is infected by bacteriophage virus.
During replication of bacteriophages within resistant cell, bacterial DNA containing resistant gene is packaged into one of the phages
The bacteriophage then goes on to transfer the resistant gene to a non-resistant cell that incorporates it into its genes via recombination

40

How does antimicrobial resistance transfer by transformation?

Resistant cell carries the gene on a chromosome of plasmid
The resistant cell dies, and releases its DNA
The free DNA is picked up by the competent non-resistant cell, that has now acquired resistance

41

What happens once antimicrobial resistant is acquired by another cell?

It can go on to replicate so that it's off-spring now possess the resistance gene

42

How can antibiotic activity be measured?

Disc sensitivity tests
Minimum inhibitory concentration

43

What happens in disc sensitivity tests?

Discs of antimicrobials are placed in a petri-dish containing clear agar, where a culture of bacteria is to be grown

44

How are the results of a disc sensitivity test interpreted?

The size of the clear agar around each disc correlates with its effectiveness

45

What happens in a minimum inhibitory concentration test?

There are two control test tubes, one with no antibacterials and bacteria, and one with no antibacterials and no bacteria.
The concentration of antibacterial is halved each test tube, and observe to see when no bacterial growth is observed- when the broth is not turbid

46

What are the types of beta-lactams?

Penicillins
Cephalosporins
Carbapenums
Monobactams

47

Give 5 examples of penicillins

Benzylpenicillin
Amoxicillin
Flucloxacillin
Co-amoxiclav
Tazocin

48

What is co-amoxiclav?

Amox and clavulanate

49

What is tazocin?

Piperacillin + tazobactam

50

Give an example of a cephalosporin?

Ceftriaxone

51

Give an example of a carbapenum

Meropenum

52

Give an example of a monobactam

Aztreonam

53

What is penicillin mainly active against?

Streptococci

54

What is amoxicillin active against?

Gram +ve, some gram -ve

55

What is flucloxacillin active against?

Staphylococci and streptococci

56

Give two beta-lactamase inhibitor combinations

Co-amoxiclav
Tazocin

57

What is co-amoxiclav active against?

Gram +ve
Anaerobes
More gram -ve than other penicillins

58

What is Tazocin active against?

Same as co-amoxiclav, and even more gram negative, including pseudomonas

59

How are cephalosporins organised?

Into generations

60

How do each generation of cephalosporin differ?

Each generation has increased activity against gram -ve and decreased activity against gram +ve

61

What is the advantage of cephalosporins over penicillin?

More broad spectrum drug

62

What is the disadvantage of cephalosporins over penicillins?

No anaerobes activity

63

Where does ceftriaxone have good activity?

In the CSF

64

What are there concerns over regarding cephalosporins?

Association with C. Difficile

65

What are the advantages of meropenum?

Very broad spectrum, including anaerobes
Active against most Gram -ve
Generally safe in penicillin allergy

66

When are meropenum not safe in penicillin allergy?

Anaphylaxis

67

What is vancomycin active against?

Most gram +ve

68

What is the resistance situation regarding vancomycin?

Some enterococci are resistant
Resistance in staphs is rare

69

What is the problem with vancomycin?

Not absorbed
Therapeutic drug monitoring

70

When is vancomycin given orally?

C. Difficle only

71

Why is therapeutic drug monitoring required for vancomycin?

Narrow therapeutic window

72

What is the activity of teicoplanin similar to?

Vancomycin

73

What is the advantage of teicoplanin over vancomycin?

Easier to administer

74

What are the similarities between tetracyclines and doxycycline?

Similar spectrum
Oral only

75

Where are tetracycline and doxycycline used?

Broad-spectrum, but specific use in penicillin allergy, usually from gram +ve
Atypical pathogens in pneumonia
Chlamydia and some protozoa

76

Who shouldn't tetracycline and doxycycline be given to?

Children under 12 years

77

Why shouldn't tetracycline and doxycycline be given to children under 12 years?

Stains teeth and bones

78

What is the most common aminoglycoside?

Gentamicin

79

What is gentamicin active against?

Profound activity against gram negatives

80

Where does gentamycin have good activity?

In the blood and urine

81

What is the problem with gentamicin?

Potentially nephrotoxic/ototoxic

82

What is required with gentamicin?

Therapeutic drug monitoring

83

What is gentamicin generally reserved for?

Severe gram -ve sepsi

84

Give two macrolides

Erythromycin
Clarithromycin

85

What is good about erythromycin?

Well distributed, including intracellular penetration

86

Where is erythromycin used?

Alternative to penicillin for mild gram +ve infections
Active against atypical respiratory pathogens

87

What is the most common example of quinolone?

Ciprofloxacin

88

What is the mechanism of action of ciprofloxacin?

Inhibit DNA gyrase

89

What is ciprofloxacin active against?

Very active against atypical pathogens

90

What is the problem with ciprofloxacin?

Increasing resistance
Risk of C. Difficile

91

What is the mechanism of action of trimethoprim and sulphonamides?

Inhibitors of folic acid synthesis

92

When is trimethoprim used alone in the UK?

UTI

93

What is co-trimoxazole?

Sulphamethoxazole and trimethoprim

94

What is co-trimoxazole used for?

Treat PCP
Has activity against malaria

95

What are the classes of antifungals?

Azoles
Polyenes

96

What are azoles active against?

Yeasts, and sometimes molds

97

What is the mechanism of action of azoles?

Inhibits cell membrane synthesis

98

Give an example of an azole?

Fluconazole

99

What is fluconzole used for?

Treat Candida

100

What is itra/vori/posaconazole active against?

Aspergillus

101

Give two polyenes

Nystatin
Amphotericin

102

What is the mechanism of action polyenes?

Inhibit cell membrane function

103

What is nystatin used for?

Topical treatment of Candida

104

What is amphotericin used for?

IV treatment of systemic fungal infection, e.g. Aspergillus

105

Give two antivirals

Aciclovir
Oseltamivir

106

What is the mechanism of action of aciclovir?

When phosphorylated, it inhibits viral DNA polymerase

107

What is aciclovir active against?

Herpes simplex
Varicella zoster

108

Give two things caused by herpes simplex

Genital herpes
Encephalitis

109

Give two things caused by varicella zoster

Chickenpox
Shingles

110

What is the commercial name for oseltamivir?

Tamiflu

111

What is the mechanism of action of tamiflu?

Inhibits viral neuraminidase

112

What does tamiflu treat?

Influenza A and B

113

What conditions require specialist antivirals for treatment?

HIV
HBV
HCV
CMV

114

What kind of antimicrobial is metronidazole?

Antibacterial and antiprotozotal

115

What bacteria is metronidazole active against?

Anaerobic

116

What protozoa is metronidazole active against?

Amoebae
Giardia
Trichomonas

117

What does amoebae cause?

Dysentry

118

What does giardia cause?

Diarrhoea

119

What does trichomonas cause?

Vaginitis

120

What is the purpose of antimicrobial stewardship?

Aims to guide practitioners on how to use antimicrobials in children, young people, and adults, with the outcome of slowing the progress of antimicrobial resistance. This will hopefully ensure that antimicrobials remain an effective treatment for infection