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CSP1 > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

What is selective toxicity?

A

Where compounds harm the pathogen but not the host

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2
Q

Define antimicrobial

A

Any substance active against microbes

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3
Q

Define antibiotic

A

Naturally occurring product active against bacteria

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4
Q

Define broad spectrum

A

Kills most germs gram positive and negative or anaerobes

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5
Q

Define narrow spectrum

A

Kills narrow range of microbes

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6
Q

Define bactericidal

A

Actively kills bacteria

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7
Q

Define bacteriostatic

A

Prevents bacteria multiplying

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8
Q

What does an antibiotic’s role of being bactericidal or bacteriostatic depend on?

A
  • microorganism number (if lots of bacteria less likely to be bactericidal)
  • antibiotic concentration (if low may not be sufficient to kill so not cidal)
  • is immune system compromised as affects antibiotic efficacy
  • infection site penetration capability
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9
Q

Bactericidal agent examples

A

Penicillin
Beta lactams
Aminoglycosides

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10
Q

Bacteriostatic agent examples

A

Tetracyclines
Chloramphenicol
Azithromycin

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11
Q

What are synergistic antibiotics?

A

Combined activity is greater than sum of individual activities

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12
Q

Example of synergistic antibiotics

A

Beta lactams

Aminoglycoside

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13
Q

antagonistic antibiotics define

A

Activity of 1 drug is compromised by other

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14
Q

Example of antagonistic antibiotics

A

Tetracycline and chloramphenicol with beta lactam or aminoglycoside
2 beta lactams together (penicillin and flucloxacillin in staph)

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15
Q

What is the significance of a therapeutic index?

A

Narrower index means more likely to be toxic

= toxic/therapeutic

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16
Q

Example of an antibiotic with a high therapeutic index

A

Beta lactam

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17
Q

Example of an antibiotic with a low therapeutic index

A

Aminoglycosides

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18
Q

What do beta lactams and glycopeptides do?

A

Inhibit cell wall synthesis

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19
Q

What do quinolones do?

A

Inhibit DNA gyrase

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20
Q

What does trimethoprim and sulfonamides do?

A

Inhibit folic acid metabolism

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21
Q

What do polymixins do?

A

Destroy cytoplasmic membrane structure

22
Q

What does rifampicin do?

A

Inhibits DNA directed RNA polymerase

23
Q

What do macrolides, clindamycin and chloramphenicol do?

A

Inhibit protein synthesis

50S inhibitors

24
Q

What do aminoglycosides and tetracyclines do?

A

Inhibit protein synthesis

30S inhibitors

25
Q

Examples of antibiotics against gram positive bacteria

A 
Penicillins against strep, staph, listeria
Fusidic acid
Macrolides against strep
Clindamycin - strep
Glycopeptides against strep and staph
Oxazolidinones - strep and staph
Daptomycin - strep and staph
26
Q

Examples of antibiotics against gram negative bacteria?

A 
Polymixin
Trimethoprim
Aminoglycosides - also against strep and staph which are gram positive
Monobactams
Temocillin
27
Q

Examples of broad spectrum antibiotics

A 
Beta Lactams
(Carbapenems
Amoxicillin
Piperacillin
Cephalosporins)

Chloramphenicol - also positive, negative, anaerobes
Tetracycline - also positives, negative, anaerobes

28
Q

What is the bacterial cell wall like?

A
  • peptidoglycan

- not contained in eukaryote cell wall

29
Q

What do penicillins do? Use, dose, admin, side effects

A
  • inhibit cell wall synthesis
  • gram positive
  • oral and IV
  • 4-6 times a day dose
  • penetrate most tissues inc. meninges
  • side effect allergy IgE mediated anaphylaxis,
  • pregnancy safe
  • for streptococcal and meningococcal disease
  • produces beta lactamase and alters protein binding protein to bacteria
  • resistance to many staphylococcus and S. penumoniae, worldwide gonococcal
  • rash with allopurinol
30
Q

Amoxicillin

A
  • inhibits cell wall synth
  • gram positive and negative
  • oral and IV
  • 3 x a day
  • penetrates most
  • penicillin allergy, fever, neutropenia, mononucleosis
  • pregnancy safe
  • resistance staphylococci and pneumoniae, worldwide gonococcal
  • for streptococcal drug choice if not sore throat, listeria
  • produces beta lactamase and PBP
  • rash with allopurinol
31
Q

Flucloxacillin

A
  • inhibits cell wall synth
  • gram positive
  • oral and IV
  • 4 x a day
  • penetrates most
  • penicillin allergy, rash, leukopenia
  • pregnancy
  • same resistance as pen
  • S. aureus drug of choice except MRSA
  • alters PBP
32
Q

Co-amoiclav

A
  • amoxicillin and clavulanic acid
  • inhibits cell wall synth and beta lactamase inhibitor
  • gram +, -, anaerobes
  • oral and IV
  • 3 x a day
  • penetrates most
  • liver injury
  • MRSA resistance to it
  • for polymicrobial infections
  • alters PBP, impermeability, efflux
33
Q

Piptazobactam

A
  • piperacillin and tazobactam
  • inhibits cell wall and beta lactamase inhibitor
  • gram +, -, anaerobes
  • IV
  • 3-4 x day
  • penetrates most
  • pen allergy, neutropenia, hypernatremia
  • MRSA resistant
  • for polymicrobial inf.
  • PBPs, efflux, impermeability
  • interacts with methotrexate
34
Q

Cefuroxime

A
  • cell wall
  • +, -, pseudomonas
  • IV
  • 3 x day
  • penetrates most
  • allergy, C. difficile
  • pregnancy and children
  • MRSA res.
  • for pneumonia, intra ab serious and UTIs
  • PBP, efflux, impermeability, beta lactamases
35
Q

Ceftriaxone

A 
- cell wall
\+, -, not pseudomonas
- IV
- 1/2 a day
- penetrates most and inflamed meninges
- allergy, C. difficile
- MRSA resistant
- for meningitis and pneumonia
- PBPs, efflux, imp.
36
Q

Ceftazidime

A
  • cell wall
    • and -, pseudomonas
  • IV
    3 x day
  • penetrates most and inflamed meninges
  • allergy, C. difficile
  • MRSA resistant
  • for UTIs, inta ab, not for community acquired infection
  • PBPs, efflux, beta lactamase, impermeability
37
Q

Carbapenems

A
  • cell wall, beta lactamase inhibits
  • +, -, anaerobes, pseudomonas
  • IV
  • 3 x day
  • penetrates most inc. inflamed mininges
  • allergy, rash, seizures
  • MRSA resistant
  • for polymicrobial inf.
  • PBP, efflux, imp
38
Q

Glycopeptides - vancomycin

A
  • cell wall
  • +, anaerobes
  • IV
  • 1/2 x day
  • poor penetration into CSF
  • nephrotoxic
  • VRE resistant
  • for problem gram positive infections
  • alters binding site
39
Q

Which agents inhibit protein synthesis?

A 
Aminoglycosides
Tetracyclines
Chloramphenicol
Macrolides (erythromycin, clarithromycin)
Clindamycin
Fusidic acid
40
Q

Aminoglycosides - gentamicin, amikacin

A
  • acts on 30S ribosome
  • gram +, -, pseudomonas
  • IV
  • 1 a day
  • water soluble, poor lung and CNS penetration
  • nephrotoxicity and ototoxicity
  • gram - org resistant some
  • use for serious systemic sepsis
  • efflux, imp
  • nephrotoic with vancomycin, colistin
41
Q

Macrolides - erythromycin, azithromycin, clrithromycin

A
  • acts on 50S ribosome
  • bacteriostatic
  • gram +
  • oral and IV
  • 1/2 x day
  • excellent IC penetration
  • children
  • QT prolong, inhibits P450, otitis media, pharyngitis, legionnairs
  • staph and strep resistance
  • for atypical agents, pen allergy and STIs
  • mutates binding site
42
Q

Which drugs affect nucleic acid metabolism

A
  • quinolones
  • rifampicin
    -metronidazole
    (nucleic metabolism similar in bacteria to mammals so selective toxicity is often poor except with these)
43
Q

Quinolones

A
  • inhibits DNA gyrase
  • +, staph not strep, -, pseudomonal
  • oral and IV
  • 2 x a day
  • meninges and most penetrate
  • not pregnant
  • lowers seizure threshold, tendon rupture
  • high resistance rates
  • UTI, intra abdom,
  • not for pneumonia
  • efflux and imperm
44
Q

Examples of antifolates

A

Sulphonamides (inhibits dihydropteroate synthase)

Trimethoprim (inhibits dihydrofolate reductase which is in human cells to but is much more active on bacterial enzyme)

45
Q

Role of dihydrofolate reductase

A

Dihydrofolate to tetrahydrofolate

- trimethoprim targets

46
Q

Role of dihydropteroate synthase

A

Forms dihydropteroate from first molecules

Targeted by sulphonamide

47
Q

Examples of membrane disorganising agents

A

Amphotericin (antifungal agent)
Colistin (polymyxin)
Daptomycin

48
Q

Qualities of an ideal antibiotic

A
  • selectively toxicity
  • reach and concentrate target organ
  • reach good levels in body fluids infected
  • minimally toxic
  • does not select resistance
  • inexpensive
49
Q

Antibiotic misuse

A

Widely prescribed - often when conditions did not require them
- agricultural use (dose cattle to increase yield, battery farming to control infection)

50
Q

Antimicrobial resistance problems

A 
UTIs
RTIs
Neisseria gonorrhea
M. TB
DIarrhoeal disease
Penicillin resistance
MDR
Salmonella 
H. Influenzae
Growing hospital resistant infections (methicillin resistant S. aureus, enterococci)
Need in emergency department

CSP1 (20 decks)

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