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Principles of disease > Antimicrobial chemotherapy > Flashcards

Antimicrobial chemotherapy Flashcards

(64 cards)

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1
Q

Define ‘bactericidal’

A

antimicrobial that kills bacteria (eg penicillins)

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2
Q

Define bacteriostatic

A

antimicrobial that inhibits growth of bacteria (eg. erythromycin)

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3
Q

Define a ‘sensitive’ organism

A

Organism that is inhibited or killed by levels of antimicrobial at site of infection

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4
Q

Define a ‘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, orally or parenterally
Topical - Applied to surface, skin or mucous membranes e.g. conjunctiva
Parenteral - intra-venously (iv), intra-muscularly (im), subcutaneously

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8
Q

What are the 3 mechanisms of action of antimicrobial agents

A

Inhibition of:

cell wall synthesis
protein synthesis
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 synthesis by inhibiting enzymes responsible for cross-linking carbohydrate chains

(Peptidoglycan is important structural component of bacterial cell wall and enzymes involved 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

Inhibit cell wall synthesis - at a prior stage than B-lactams
only act 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

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 aminoglycosides 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

Aminoglycoside, toxic - requires careful dosing regime and motoring of levels

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18
Q

What are the uses of macrolides and tatracyclines

A

Treatment of gram positive infections in patients with penicillin allergy
Cannot be used without lab testing

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19
Q

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

A

Oxazolidonones (protein synthesis inhibitor)
Good activity against MRSA
Typically in reserve for 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 drawbacks?

A

Fluoroquinolone (nucleic acid inhibitor)
Against gram negative organisms
Can be taken orally
Not used in children

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23
Q

Describe inherent/intrinsic resistance

A

Some cases all strains of a species are naturally resistant to antibiotic
Inability of drug to penetrate bacterial cell wall to exert its action

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24
Q

What is the first way in which acquired resistance can be acquired in bacteria

A
  1. Spontaneous mutation during multiplication of bacterial DNA can result in change in structure or function which no longer allows antibiotic to act, target may have changed
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25
What is the second way in which acquired resistance may be acquired?
2. resistance genes can spread from organism to organism or species to species Most common mode by plasmids (extra chromosomal packages for DNA) or on transposons (packets of DNA which insert themselves into chromosome)
26
What are the 2 mechanisms of resistance to β–lactam antibiotics?
β-lactamase production - bacterial enzymes cleave β–lactam ring of antibiotic and inactive it Alteration of penicillin binding protein (PBP) target site - Mutations in PBP genes modifies target site and β–lactams will no longer bind
27
What drug is β-lactamase resistant
Flucloxacillin - can be used to treat β-lactamase producing staph. aureus (staph.aureus produce β-lactamase)
28
What are ESBL's and what are the implications of their existence
Extended spectrum β–lactamases (ESBLs) - increasing problem in hospitals Produced by some Gram negative organisms and can break down third generation cephalosporins and penicillins Render organism resistant to all β–lactam antibiotics
29
What glycopeptide resistant bacteria has appeared recently and what are the implications of this mutation?
Vancomycin resistant enterococci (VREs) Mechanism of resistance might spread from enterococci to Staph aureus, producing vancomycin resistant Staph aureus Staph aureus more significant pathogen than enterococci
30
Describe the spectrum of Benzyl penicillin (penicillin G)
Best choice for IV treatment of serious pneumococcal, meningococcal and strep pyogenes Gram +ve
31
Describe the spectrum of amoxicillin/ampicillin
Streptococci and coliforms Gram -ve
32
Describe the spectrum of co-amoxiclov
Effective against B-lactamase producing coliforms
33
Describe the spectrum of flucloxacillin
Effective against staph infections
34
Describe the spectrum of piperacillin
Enterococcus faecalis Pseudomonas species Extended Gram -ve cover
35
Describe the spectrum of cephalosporins
Activity against Gram -'ve organisms increases from 1st through 3rd generation Activity against Gram +'ve organisms decreases from 1st through 3rd generation Not used as much now, may encourage Ciff D infections
36
How must cephalosporins be taken?
Parenteral use only
37
Describe the specrum of aminoglycocides
Gram -'ve organisms Effective against staphlococci but not streptococci Gentamicin cheapest and most common aminoglycocide
38
Describe the spectrum of glycopeptides
Only gram +'ve organisms - anaerobic + aerobic Vancomycin most common example
39
Describe the spectrum of action of macrolides
Mainly against gram +'ve organisms Alternative to penicillin for patients with penicillin allergy
40
Describe the spectrum of action of Quinolones
Active against nearly all gram -'ve organisms Mainly used in treatment of community acquired pneumonia
41
Describe the spectrum of action of metronidazole
Gram +'ve and -'ve anaerobes
42
Describe the spectrum of action of fusidic acid
Disrupts bacterial protein synthesis Anti-Staphyloccocal In combo with flucloxacillin
43
Describe the spectrum of action of trimethoprim
Used in urinary infections
44
Describe the spectrum of action of tetracyclines
Used in genital tract and urinary tract infections
45
Describe the spectrum of action of clindamycin
Gram +'ve organisms
46
What infection is linezolid used against
MRSA
47
What infection is fidaxomicin used against
C. diff
48
What infection is daptomycin used against?
MRSA Vancomycin Resistant Enterococci
49
What are the 4 classes of anti-fungal drugs?
Polyenes Echinocandins Allyamines Azoles
50
Describe the mechanism of polyenes
Bind to ergosterol Present in fungal cell wall but not bacterial Increases permeability of cell wall Binds to mammalian sterols making polyenes toxic
51
Describe the use of amphotericin B and Nystatin
Amphotericin B - IV for serious yeast infections and other fungal infections Very toxic Nystatin - topically or in oral suspension for serious fungal infection Not intra-venous agent
52
Describe the mechanism of Azoles
Inhibit ergesterol synthesis
53
What is fluconazole used to treat?
Yeast infections
54
What are voriconazole and intraconazole used to treat?
Aspergillosis (fungal infection caused by aspergillus, affects airways)
55
Describe the mechanism of allylamines
Suppress ergosterol synthesis but act at different stage of synthetic pathway from azoles
56
Describe the use of Terbinafine
Fungal infections of skin and nails
57
Describe the mechanism of echinocandins
Inhibit synthesis of glucan polysaccharide in several types of fungi
58
What are echinocandins used for?
Serious candida and aspergillus infections
59
Describe anti-herpes virus drugs
All become latent and include: Herpes simplex virus (HSV) Epstein-barr virus (EBV) Cytomegalovirus (CMV) Varicella-Zoster Virus (VZV).
60
Describe the mechanism and function of Aciclovir
Nucleotide analogue Converted into active form by enzyme Specific for virus-infected cells Not very toxic Extremely active against HSV and VZV IV used for serious, Oral for less serious
61
Describe the use of valaciclovir and famciclovir
Related to aciclovir - Used in oral treatment of HSV and shingles
62
Describe the use of valganciclovir
Prodrug of ganciclovir -> alternative treatment for CMV High levels of bone marrow toxicity (prodrug is a medication or compound that, after intake, is metabolised into a pharmacologically active drug. Instead of administering a drug directly, a corresponding prodrug can be used to improve how the drug is absorbed, distributed, metabolised, and excreted)
63
Describe the use of foscarnet (Foscavir)
Used for HSV, VZV and CMV Highly nephrotoxic (toxic to kidneys)
64
Describe the use of Cidofovir
Used for CMV retinitis (retinal eye disease)

Principles of disease (47 decks)

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