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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
What is the mode of action of linezolid?
Inhibition of protein synthesis
26
What type of drug us daptomycin?
Cyclic lipopeptide
27
What is the mode of action of daptomycin?
Inhibition of protein synthesis
28
What is the mode of action of trimethoprim and sulphamethoxazole?
Inhibition of nucleic acid synthesis by inhibiting purine synthesis
29
What is co-trimoxazole composed of?
Trimethoprim and Sulphamethoxazole
30
What is the advantage of co-trimoxazole over other broad spectrum agents such as cephalosporins?
Less likely to cause Clostidium difficile infections
31
Trimethoprim is used commonly to treat which kind of infection?
Urinary tract
32
What type of drug is ciprofloxacin?
Fluoroquinolone
33
What is the mode of action of fluoroquinolones?
Directly inhibit DNA synthesis
34
What type of drug is levofloxacin?
Quinolone
35
How are fluoroquinolones administered?
Orally and parenterally
36
Which type of bacteria are more susceptible to ciprofloxacin?
Gram negative including Pseudomonas auruginosa
37
Can children be prescribed ciprofloxacin?
No as it interferes with cartilage growth
38
Gram negative bacteria are always resistant to which drug?
Vancomycin
39
Streptococci are always resistant to which type of drugs?
Aminoglycosides
40
What are the 2 ways in which resistance is acquired by bacteria?
1) Spontaneous mutation | 2) Spread of resistance genes to bacteria from the same or different species trough plasmids or transposons
41
What are β-lactamases?
Bacterial enzymes which cleave the β-lactam ring of the antibiotic rendering it inactive
42
Where would we commonly encounter β-lactamase producing bacteria?
1) Staphylococcus aureus hospital strains | 2) Gram negative bacilli (i.e. E.coli)
43
What are the 2 ways to overcome the presence of β-lactamase? Give example for each.
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
Which type of bacteria produce ESBLs (Extended Spectrum β-Lactamases)?
Gram negative
45
What property does ESBL production give to bacteria?
Resistance to all β-lactam antibiotics
46
Are CPE (Carbamenemase Producing Enterobacteriaceae gram positive or negative?
Negative
47
What properties do CPEs (Carbapenemase Producing Enterobacteriaceae) have in terms of antibiotic susceptibility?
Extremely resistant bacteria resistant to carbapenems and often multiple other classes leaving no other option for treatment
48
Apart from β-lactamase production, which is the other way that bacteria acquire resistance against β-lactams?
Modification of their PBPs so that the drug no longer binds
49
How is β-lactam resistance achieved in MRSA?
Alteration of PBPs
50
MRSA is resistant to which classes of drugs?
1) Penicillins | 2) Cephalosporins
51
What type of bacteria emerged having vancomycin resistance?
VRE (Vancomycin Resistant Enterococci) - Enterococcus faecalis and Enterococcus faecium
52
How is resistance to vancomycin achieved by VREs?
Alteration of peptidoglycan precursor in which the drug binds
53
In what type of bacteria does benzyl penicillin act against?
Gram positive AND ONE EXCEPTION - meningococcus
54
For what type of infections is benzyl penicillin primarily used?
Serious pneumococcal, meningococcal and Streptococcus pyogenes infection
55
In what type of bacteria do amoxicillin and ampicillin act against?
Streptococci and some coliforms
56
In what type of bacteria does co-amoxiclav act against?
Streptococci and coliforms INCLUDING β-lactamase producing ones
57
What is the first choice of treatment for staphyloccocal infections?
Flucloxacillin
58
What two drugs constitute the preparation Tazocin?
Piperacillin and tazobactam
59
What is tazobactam?
β-lactamase inhibitor
60
Piperacillin is good for treating what type of infection?
1) Enterococcus faecalis 2) Pseudomonas infetions 3) Serious intra-abdominal infections
61
Why is piperacillin good for treating serious intra-abdominal infections?
Good anti-anaerobic activity
62
Imipenem and meropenem belong to a sub-group of penicillin. Which one?
Carbapenems
63
Name a first, second and third generation cephalosporin.
First: Cephradine Second: Cefuroxine Third: Ceftriaxone
64
How is the activity against gram positives and gram negatives changes as cephalosporins move from the first to third generation?
Gram negative activity increases while gram positive activity decreases
65
In what type of bacteria do aminoglycosides act against?
Gram negatives including pseudomonas and staphylococci
66
In what type of bacteria do glycopeptides act against?
Gram positives ONLY - both aerobic and anaerobic
67
Which type of drugs is effective against organisms causing atypical pneumonia?
Macrolides
68
Which type of drugs is used as an alternative to penicillin in patients with allergy?
Macrolides
69
Macrolide azythromycin is used to treat which type of infection?
Clamydia
70
Quinolones are active against which type of bacteria?
Gram negatives including pseudomonas
71
What drug class is the only possibility for oral therapy in the treatment of pseudomonas infections?
Quinolones
72
For what type of pneumonia can levofloxacin be used?
Atypical
73
Which drug can be used against gram positive (Clostridia) and gram negative (Bacteroids) anaerobes?
Metronidazole
74
What is the only purpose of fusidic acid?
Anti-staphylococcal
75
What is fusidic acid commonly used with and why in the treatment of staphylococcal infections?
Flucloxacillin because Staph aureus can readily develop resistance to it
76
Which drug can be used in the treatment of staphylococcal osteomyelitis and pneumonia due to its ability to diffuse well in bones and tissues?
Fusidic acid
77
Tetracyclines which are broad agents used limited in some conditions. Name 2
1) Genital tract infection (Chlamydia) | 2) Respiratory tract infection (Mycoplasma pneumoniae)
78
What is the spectrum of action of clindamycin?
Gram positives (staphylococci and streptococci) and anaerobes
79
What are the advantages and disadvantages of clindamycin?
Advantages 1) Good tissue penetration 2) Can be taken orally Disadvantages Can cause pseudo-membranous colitis
80
Where can linezolid be used?
MRSA
81
Linezolid can caus be which side effect?
Bone marrow depression
82
What is daptomycin used for?
MRSA
83
Where can fidaxomicin be used?
Clostridium difficile infection
84
Where is nalidixic acid used?
Gram negative coliform urinary infection
85
Against which bacteria is nitrofurantoin effective?
Most gram negatives except proetus and pseudomonas and some gram positives
86
What 2 classes of drugs are the most common for causing allergic reactions?
Penicillins and cephalosporins (β-lactams)
87
What type of allergic reaction is anaphylactic shock?
Immediate hypersitivity
88
How does delayed hypersensitivity usually presents?
Rash is the most common but fever, serum sickness and erythema nodosum can also occur
89
What type of hypersensitivity is Stevens - Johnson syndrome?
Delayed
90
Stevens - Johnson syndrome is associated with which type of drugs?
Sulphonamides

MBChB Year 1 (1 decks)

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