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MBChB Year 1 > Antimicrobial Chemotherapy > Flashcards

Antimicrobial Chemotherapy Flashcards

1
Q

What are the 3 sites of antibiotic action?

A

1) Inhibition of cell wall synthesis
2) Inhibition of protein synthesis
3) Inhibition of nucleic acid synthesis

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2
Q

What type of antibiotic are penicillin and cephalosporins?

A

β-lactams

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3
Q

What is the mode of action of β-lactam antibiotics?

A

Bind to PBPs (Penicillin Binding Proteins) which are essential for the peptidoglycan wall synthesis as they cross link the carbohydrate chains, disrupting the process. The bacterium is then lysed by autolytic enzymes.

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4
Q

How is the first natural β-lactam discovered by Sir Fleming called?

A

Benzyl penicillin (Penicillin G)

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5
Q

What type of bacteria show resistance against benzyl penicillin?

A

Gram negative

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6
Q

What type of drugs are vancomycin and teicoplanin?

A

Glycopeptides

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7
Q

What is the mode of action of glycopeptides?

A

Inhibit cell wall synthesis by inhibiting the assembly of a peptidoglycan precursor

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8
Q

Glycopeptides kill which kind of bacteria?

A

Gram positives ONLY

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9
Q

How are glycopeptides administered?

A

Parenterally as they are not absorbed by the GI tract

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10
Q

What precautions have to be taken when administering vancomycin?

A

1) Infused slowly over a period of hours

2) Monitor serum levels throughout

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11
Q

What type of toxicities are associated with vancomycin?

A

1) Ototoxicity
2) Nephrotoxicity
3) Skin rash

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12
Q

What is the mode of action of aminoglycosides?

A

Inhibition of protein synthesis

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13
Q

What type of drug is gentamicin?

A

Aminoglycoside

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14
Q

What is the primary use of aminoglycosides?

A

Treat gram negative (i.e. coliform) infections

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15
Q

What is the main mode of administration of aminoglycosides?

A

Parenteral

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16
Q

How does sensitivity to aminoglycosides differs between staphylococci and streptococci?

A

Staphylococci are sensitive to the drug while streptococci are not

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17
Q

What is the routine dosing of gentamicin?

A

Once daily

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18
Q

What toxicities are associated with gentamicin?

A

1) Ototoxicity

2) Nephrotoxicity

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19
Q

What precautions have to be taken when administering gentamicin?

A

1) Carefully determining the dosing regime

2) Monitoring of serum levels

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20
Q

What is the mode of action of macrolides and tetracyclines?

A

Inhibition of protein synthesis

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21
Q

What type of drugs are erythromycin and clarithromycin?

A

Macrolides

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22
Q

When are macrolides typically used?

A

Alternatives to penicillin in treating gram positive infections in patients who are allergic to it

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23
Q

> 10% of 3 bacteria strains have been identified to be resistant to macrolides. Which are they?

A

1) Staphylococcus aureus
2) Streptococcus pyogenes
3) Streptococcus pneumoniae

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24
Q

What type of drug is linezolid?

A

Oxazolidinone

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25
Q

What is the mode of action of linezolid?

A

Inhibition of protein synthesis

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26
Q

What type of drug us daptomycin?

A

Cyclic lipopeptide

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27
Q

What is the mode of action of daptomycin?

A

Inhibition of protein synthesis

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28
Q

What is the mode of action of trimethoprim and sulphamethoxazole?

A

Inhibition of nucleic acid synthesis by inhibiting purine synthesis

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29
Q

What is co-trimoxazole composed of?

A

Trimethoprim and Sulphamethoxazole

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30
Q

What is the advantage of co-trimoxazole over other broad spectrum agents such as cephalosporins?

A

Less likely to cause Clostidium difficile infections

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31
Q

Trimethoprim is used commonly to treat which kind of infection?

A

Urinary tract

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32
Q

What type of drug is ciprofloxacin?

A

Fluoroquinolone

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33
Q

What is the mode of action of fluoroquinolones?

A

Directly inhibit DNA synthesis

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34
Q

What type of drug is levofloxacin?

A

Quinolone

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35
Q

How are fluoroquinolones administered?

A

Orally and parenterally

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36
Q

Which type of bacteria are more susceptible to ciprofloxacin?

A

Gram negative including Pseudomonas auruginosa

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37
Q

Can children be prescribed ciprofloxacin?

A

No as it interferes with cartilage growth

38
Q

Gram negative bacteria are always resistant to which drug?

A

Vancomycin

39
Q

Streptococci are always resistant to which type of drugs?

A

Aminoglycosides

40
Q

What are the 2 ways in which resistance is acquired by bacteria?

A

1) Spontaneous mutation

2) Spread of resistance genes to bacteria from the same or different species trough plasmids or transposons

41
Q

What are β-lactamases?

A

Bacterial enzymes which cleave the β-lactam ring of the antibiotic rendering it inactive

42
Q

Where would we commonly encounter β-lactamase producing bacteria?

A

1) Staphylococcus aureus hospital strains

2) Gram negative bacilli (i.e. E.coli)

43
Q

What are the 2 ways to overcome the presence of β-lactamase? Give example for each.

A

1) Introduce a second component in the antibiotic which will act as a β-lactamase inhibitor - i.e. co-amoxiclav which contains amoxicillin and the inhibitor clavulanic acid
2) Modify the antibiotic to make it resistant to cleavage by the β-lactamase - i.e. flucloxacillin

44
Q

Which type of bacteria produce ESBLs (Extended Spectrum β-Lactamases)?

A

Gram negative

45
Q

What property does ESBL production give to bacteria?

A

Resistance to all β-lactam antibiotics

46
Q

Are CPE (Carbamenemase Producing Enterobacteriaceae gram positive or negative?

A

Negative

47
Q

What properties do CPEs (Carbapenemase Producing Enterobacteriaceae) have in terms of antibiotic susceptibility?

A

Extremely resistant bacteria resistant to carbapenems and often multiple other classes leaving no other option for treatment

48
Q

Apart from β-lactamase production, which is the other way that bacteria acquire resistance against β-lactams?

A

Modification of their PBPs so that the drug no longer binds

49
Q

How is β-lactam resistance achieved in MRSA?

A

Alteration of PBPs

50
Q

MRSA is resistant to which classes of drugs?

A

1) Penicillins

2) Cephalosporins

51
Q

What type of bacteria emerged having vancomycin resistance?

A

VRE (Vancomycin Resistant Enterococci) - Enterococcus faecalis and Enterococcus faecium

52
Q

How is resistance to vancomycin achieved by VREs?

A

Alteration of peptidoglycan precursor in which the drug binds

53
Q

In what type of bacteria does benzyl penicillin act against?

A

Gram positive AND ONE EXCEPTION - meningococcus

54
Q

For what type of infections is benzyl penicillin primarily used?

A

Serious pneumococcal, meningococcal and Streptococcus pyogenes infection

55
Q

In what type of bacteria do amoxicillin and ampicillin act against?

A

Streptococci and some coliforms

56
Q

In what type of bacteria does co-amoxiclav act against?

A

Streptococci and coliforms INCLUDING β-lactamase producing ones

57
Q

What is the first choice of treatment for staphyloccocal infections?

A

Flucloxacillin

58
Q

What two drugs constitute the preparation Tazocin?

A

Piperacillin and tazobactam

59
Q

What is tazobactam?

A

β-lactamase inhibitor

60
Q

Piperacillin is good for treating what type of infection?

A

1) Enterococcus faecalis
2) Pseudomonas infetions
3) Serious intra-abdominal infections

61
Q

Why is piperacillin good for treating serious intra-abdominal infections?

A

Good anti-anaerobic activity

62
Q

Imipenem and meropenem belong to a sub-group of penicillin. Which one?

A

Carbapenems

63
Q

Name a first, second and third generation cephalosporin.

A

First: Cephradine
Second: Cefuroxine
Third: Ceftriaxone

64
Q

How is the activity against gram positives and gram negatives changes as cephalosporins move from the first to third generation?

A

Gram negative activity increases while gram positive activity decreases

65
Q

In what type of bacteria do aminoglycosides act against?

A

Gram negatives including pseudomonas and staphylococci

66
Q

In what type of bacteria do glycopeptides act against?

A

Gram positives ONLY - both aerobic and anaerobic

67
Q

Which type of drugs is effective against organisms causing atypical pneumonia?

A

Macrolides

68
Q

Which type of drugs is used as an alternative to penicillin in patients with allergy?

A

Macrolides

69
Q

Macrolide azythromycin is used to treat which type of infection?

A

Clamydia

70
Q

Quinolones are active against which type of bacteria?

A

Gram negatives including pseudomonas

71
Q

What drug class is the only possibility for oral therapy in the treatment of pseudomonas infections?

A

Quinolones

72
Q

For what type of pneumonia can levofloxacin be used?

A

Atypical

73
Q

Which drug can be used against gram positive (Clostridia) and gram negative (Bacteroids) anaerobes?

A

Metronidazole

74
Q

What is the only purpose of fusidic acid?

A

Anti-staphylococcal

75
Q

What is fusidic acid commonly used with and why in the treatment of staphylococcal infections?

A

Flucloxacillin because Staph aureus can readily develop resistance to it

76
Q

Which drug can be used in the treatment of staphylococcal osteomyelitis and pneumonia due to its ability to diffuse well in bones and tissues?

A

Fusidic acid

77
Q

Tetracyclines which are broad agents used limited in some conditions. Name 2

A

1) Genital tract infection (Chlamydia)

2) Respiratory tract infection (Mycoplasma pneumoniae)

78
Q

What is the spectrum of action of clindamycin?

A

Gram positives (staphylococci and streptococci) and anaerobes

79
Q

What are the advantages and disadvantages of clindamycin?

A

Advantages

1) Good tissue penetration
2) Can be taken orally

Disadvantages

Can cause pseudo-membranous colitis

80
Q

Where can linezolid be used?

A

MRSA

81
Q

Linezolid can caus be which side effect?

A

Bone marrow depression

82
Q

What is daptomycin used for?

A

MRSA

83
Q

Where can fidaxomicin be used?

A

Clostridium difficile infection

84
Q

Where is nalidixic acid used?

A

Gram negative coliform urinary infection

85
Q

Against which bacteria is nitrofurantoin effective?

A

Most gram negatives except proetus and pseudomonas and some gram positives

86
Q

What 2 classes of drugs are the most common for causing allergic reactions?

A

Penicillins and cephalosporins (β-lactams)

87
Q

What type of allergic reaction is anaphylactic shock?

A

Immediate hypersitivity

88
Q

How does delayed hypersensitivity usually presents?

A

Rash is the most common but fever, serum sickness and erythema nodosum can also occur

89
Q

What type of hypersensitivity is Stevens - Johnson syndrome?

A

Delayed

90
Q

Stevens - Johnson syndrome is associated with which type of drugs?

A

Sulphonamides

MBChB Year 1 (1 decks)

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