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1.3 POM Immunology > Antimicrobial Therapies > Flashcards

Antimicrobial Therapies Flashcards

1
Q

What type of antibiotic is prontosil?

A

Sulphonamide

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2
Q

What is prontosil used to treat? (4)

A
  1. UTIs
  2. RTIs (respiratory tract)
  3. Bacteraemia
  4. HIV prophylaxis
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3
Q

What are the 9 types of antibiotic?
(Guys Let’s Do Something to Mitigate Bacterial Antibiotic Resistance Quickly!)

A
  1. Glyopeptides
  2. Linezoid
  3. Daptomycin
  4. Sulfonamides
  5. Macrolids
  6. Beta-lactams
  7. Aminoglycosides
  8. Rifamycins
  9. Quinolones
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4
Q

What may be used in conjunction with sulphonamides?

A

Trimethoprim

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5
Q

What type of bacteria does prontosil work against?

A

Gram positive

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6
Q

Which 5 antibiotics work against gram-positive bacteria only?

A
  1. Sulphonamides
  2. Beta-lactams
  3. Glycopeptides
  4. Linezoid
  5. Daptomycin
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7
Q

What are 2 examples of sulphonamides?

A
  1. Prontosil
  2. Sulpha-methoxazole
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8
Q

How do beta-lactams act as antibiotics?

A

Cell wall
- Bind to penicillin binding proteins (PBPs)
- PBPs catalyse peptidoglycan synthesis
- Cell wall can’t be synthesised

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9
Q

What are 2 examples of beta-lactams?

A
  1. Penicillin
  2. Methicillin
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10
Q

What type of antibiotic is penicillin?

A

Beta-lactam

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11
Q

What type of antibiotic is methicillin?

A

Beta-lactam

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12
Q

What do beta-lactams bind to?

A

PBPs

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13
Q

What is the shape of a beta-lactam ring?

A

Square

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14
Q

When are antibiotics administered? (3)

A
  1. Bacterial infections
  2. Surgery —> prevent infection
  3. Cancer therapies —> weakened immune system
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15
Q

What are the 4 antimicrobial mechanisms?

A
  1. Inhibit peptidoglycan cell wall synthesis
  2. Inhibit translation
  3. Inhibit transcription
  4. Target cell membrane
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16
Q

What is an antibiotic?

A

Antimicrobial agent produced by a microorganism that kills or inhibits other microorganisms

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17
Q

What are most antibiotics produced by today? (2)

A
  1. Soil-dwelling fungi
  2. Bacteria
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18
Q

Which antibiotics are produced by soil-dwelling fungi? (2)

A
  1. Penicillin
  2. Cephalosporium
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19
Q

Which antibiotics are produced by bacteria?

A
  1. Streptomyces
  2. Bacillus
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20
Q

What is the difference between bactericidal and bacteriostatic antibiotics?

A
  1. -Cidal —> kills
  2. -Static —> stops growth
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21
Q

What is an antiseptic?

A

Topical chemical that kills/inhibits microbes

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22
Q

What does antimicrobial mean?

A

Chemical that selectively kills/inhibits microbes

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23
Q

What is the main problem of antibiotics?

A

Resistance

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24
Q

What is the antibiotic breakpoint?

A

Concentration of drug past which bacteria will develop resistance (at MIC)

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25
Q

What is the minimal inhibitory concentration (MIC)?

A

Lowest AB concentration required to inhibit growth

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26
Q

How are antibiotic dosages decided?

A

MIC

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27
Q

Why does the use of antibiotics lead to resistance?

A

Act as selection pressure

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28
Q

What are the 3 steps of bacteria developing antibiotic resistance?

A
  1. Mutation —> bacteria in population has AB resistance
  2. Selection pressure of AB
  3. AB resistant bacteria outcompete non-resistant
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29
Q

What type of gene transfer also leads to other species of bacteria gaining resistance?

A

Horizontal

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30
Q

How long after the arrival of a new antibiotic does resistance usually emerge?

A

Soon

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31
Q

What does antibiotic resistance lead to? (5)

A

In mortality, morbidity, cost
1. Inc time for therapy effectivity
2. Treatment requires other approaches eg. surgery/IV
3. Expensive therapies used
4. More toxic drugs used
5. Less effective ABs used

32
Q

Which 6 gram-negative bacteria are multi-drug resistant?

A
  1. P. aeruginosa
  2. E. coli
  3. Salmonella
  4. A. baumannii
  5. N. gonorrhoeae
33
Q

Which 5 gram-positive bacteria are multi-drug resistant?

A
  1. S. aureus
  2. S. pneumoniae
  3. C. difficile
  4. E. spp
  5. M. tuberculosis
34
Q

How do aminoglycosides act as antibiotics?

A

Translation
-Target 30S ribosomal subunit —> interfere will RNA proofreading —> inhibit protein synthesis —> damage cell membrane

35
Q

What are 2 examples of aminoglycosides?

A
  1. Gentamicin
  2. Streptomycin
36
Q

What type of antibiotic is gentamicin?

A

Aminoglycoside

37
Q

What type of antibiotic is streptomycin?

A

Aminoglycoside

38
Q

How does rifampin act as an antibiotic?

A

Translation
-Targets RpoB subunit of RNA polymerase —> inhibits translation

39
Q

Why are there issues with rifampin compliance?

A

Turn secretions orange/red

40
Q

What is a major issue of rifampicin regarding AB resistance?

A

Frequent spontaneous resistance

41
Q

What is rifampin used to treat?

A

TB

42
Q

How does vancomycin act as an antibiotic? (2)

A

Cell wall
- Targets Lipid II —> inhibit cell wall biosynthesis
- Targets D-ala residues —> inhibits cell wall crosslinks

43
Q

Which 4 antibiotics have some toxicity?

A
  1. Sulphonamides
  2. Aminoglycosides
  3. Vancomycin
    4.
44
Q

Which 3 antibiotics are only bacteriostatic?

A
  1. Sulphonamides
  2. Linezoid
  3. Macrolides
45
Q

How does linezolid act as an antibiotic?

A

Translation
- Binds to 50S rRNA subunit

46
Q

What type of bacteria does linezolid work against?

A

Gram-positive

47
Q

How does daptomycin act as an antibiotic?

A

Targets cell membrane

48
Q

Why are antibiotics selectively toxic?

A

Can kill bacterial cells without harming host cells

49
Q

Which organ can antibiotics collect in and cause issues?

A

Kidney
- If UTI —> good

50
Q

What are the 4 mechanisms of antibiotic resistance?

A
  1. Altered target protein
  2. Inactivation of antibiotic
  3. Altered metabolism
  4. Decreased drug accumulation
51
Q

How does an altered target site lead to AB resistance? (3)

A
  • Mutation —> change target protein —> AB can’t bind
  • Mutation —> different binding protein acquired
  • Target site methylated
52
Q

Which 2 bacteria acquired AB resistance via an altered target site?

A
  1. MRSA
  2. S. pneumoniae
53
Q

How is MRSA resistant to beta-lactams?

A

Acquired PBP2a with low affinity for beta-lactams

54
Q

How is streptococcus pneumoniae resistant to erythromycin?

A

erm gene acquired —> enzyme produced methylates target site in 50S ribosomal subunit

55
Q

How does an inactivation of an antibiotic work?

A

Enzymic degradation/alteration

56
Q

What are 2 examples of enzymes that can inactivate ABs?

A
  1. Beta-lactamase (bla)
  2. Chloramphenicol acety-transferase (cat)
    think: BLAck CAT
57
Q

What are 2 examples of broad-spectrum beta-lactamases?

A
  1. ESBL
  2. NDM-1
58
Q

Why does altered metabolism lead to AB resistance? (2)

A
  1. Inc production of enzyme substrate —> out-compete AB inhibitor
  2. Switch to other metabolic pathway —> bypass AB target
59
Q

How does AB resistance to sulphonamides occur?

A

Altered metabolism
- Inc production of PABA
- Switch to pathway that doesn’t use PABA

60
Q

How does decreased drug accumulation work for AB resistance? (2)

A
  1. Dec penetration of AB into bacteria
  2. Inc efflux of AB out of bacteria
61
Q

How do macrolides act as antibiotics?

A

Translation
- Target 50S ribosomal subunit —> prevent amino-acyl transfer —> truncates polypeptides

62
Q

What are 2 examples of macrolids?

A
  1. Erythromycin
  2. Azithromycin
63
Q

What type of antibiotic is erythromycin?

A

Macrolides

64
Q

What type of antibiotic is azithromycin?

A

Macrolides

65
Q

How do quinolones act as antibiotics? (2)

A

Transcription
1. Gram - —> target DNA gyrase
2. Gram + —> target topoisomerase IV

66
Q

What is special about quinolone production?

A

Completely synthetic

67
Q

What are the 3 sources of AB resistant genes?

A
  1. Plasmids
  2. Transponons —> allows gene transfer between plasmids and chromosome
  3. Naked DNA —> dead bacteria release DNA to environment
68
Q

What are the 5 non-genetic mechanisms of AB resistance? (SPIBS)

A
  1. Slow growth
  2. Persistors
  3. Intracellular location
  4. Biofilm
  5. Spores
69
Q

What are 5 reasons for AB treatment failure?

A
  1. Inappropriate choice of drug/dose/administration
  2. Poor AB penetration to target site
  3. AB resistance in commensal flora (eg. flora secrete beta-lactamase)
70
Q

How is AB resistance identified?

A
  1. Swabs —> onto agar lorn
  2. AB test strips onto agar lorn
  3. Miro-dilution
  4. PCR detection of resistance genes
71
Q

What are the 8 hospital acquired infections?

A
  1. MRSA
  2. VISA (vancomycin-insensitive)
  3. VRE (vancomycin-resistant enterococci)
  4. C. difficile
  5. E. coli
  6. P. aeruginosa
  7. A. baumannii
  8. S. maltophilia
72
Q

What are hospital-acquired infections so common? (2)

A
  1. Many infected people
  2. Lots of AB use
    —> Strong selective pressure
73
Q

What are the 7 risk factors for hospital acquired infections?

A
  1. Many ill people - immunosuppressed
  2. Crowded wards
  3. Pathogens present
  4. Broken skin - after surgery/IV/catheter
  5. Intubation in indwelling devices
  6. AB therapy suppressing normal flora
  7. Single staff in contact with many patients - spread
74
Q

How can antibiotics affect microbiota?

A

Out-compete flora

75
Q

How is AB resistance being addressed? (5)

A
  1. Prescribing strategies
  2. Dec broad-spectrum AB use
  3. Quicker identification
  4. Combination therapy (eg. coamoxiclav)
  5. Knowledge of local strains
76
Q

How can AB resistance be overcome? (2)

A
  1. Modify existing meds
  2. Combination of antibiotic and inhibitor
    - eg. coamoxiclav = amoxicillin + clavulanic acid

1.3 POM Immunology (13 decks)

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