Microbiology Antibiotics 2 Flashcards Preview

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Flashcards in Microbiology Antibiotics 2 Deck (74):
1

Fluoroquinolones example

• Ciprofloxacin
• Levofloxacin
• Moxifloxacin

2

Aminoglycosides example

• Gentamicin

3

Glycopeptides example

• Vancomycin
• teicoplanin

4

Macrolides example

• Erythromycin
• Clarithromycin

5

Tetracyclines example

• Minocycline

6

Fluoroquinolones: Used

Mainly used in hospital to treat Gram negative infection and lower resp tract infections

7

Fluoroquinolones: Action

By inhibiting DNA gyrase,

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Fluoroquinolones: Resistance

Increasingly common – mainly target site modification but also efflux pumps.

9

Fluoroquinolones:Absorption

Good oral bioavailability so po often as good as iv

10

Fluoroquinolones:Distribution

Wide tissue distribution (2-3 L/Kg)

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Fluoroquinolones:Excretion and metabolism

Excretion y metabolism (ciprofloxacin, moxifloxacin)
Renal clearance (Ciprofloxacin, moxifloxacin, levofloxacin)

12

Fluoroquinolones: Side effects

Generally safe:
• Rashes/phototoxicity
• Tendenitis and rupture
• GI upset
• OTC prolongation (moxifloxacin) - (more likely to have ventricular tachy arrhythmia)
• Hepatotoxicity

13

Spectrum-ciprofloxacin: targets

• Aerobic Gram negative bacterial (coliforms, Pseudomonas, gonococci, H. influenza, atypical chest pathogens (legionella,mycoplasma, chlamydia))
• Border line activity against S.aureus and streptococci
• Not active against anaerobes
• Some activity against M. tuberculosis

14

Spectrum – moxifloxacin: Target

• Much improved activity versus Staphylococci and Streptococci
• Poor activity vs. P.aeruginosa, better activity against anaerobes

15

Spectrum – moxifloxacin:Indications

• Community acquired chest infections (moxifloxacin/levofloxacin)
• UTI/acute pyeonephitis (ciprofloxacin, levofloxacin) NB resistanct
• Intraabdominal infection (+ metronidazole)
• Bone/joint infection
• Oral therapy of P.aeruginosa (ciprofloxacin)

16

Aminoglycosides: Action

Inhibiting of protein synthesis at ribosoms

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Aminoglycosides: Resistance by

Enzymes (aminoglycoside monitoring enzymes) but rare

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Aminoglycosides: Absorption

Intravenous/Im only
Poor oral absorption

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Aminoglycosides: Distribution

Modest tissue penetration – concentrated in the kidney and ears (toxicity)

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Aminoglycosides:Excretion

Renal excretion – accumulation in renal failure, no metabolism

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Aminoglycosides:Examples

Gentamicin
Tobramycin
Amikacin IV

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Aminoglycosides: Reduced use because

Toxicity requires therapeutic drug monitoring

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Aminoglycosides: Antimicrobial spectrum

Broad Gram negative activity
Coliform
P.aeruginosa
No anaerobic activity

24

Aminoglycosides: Indications

1. In combination therapy for intra abdominal infection
2. In combination therapy for infective endocarditis
3. In combination therapy for neutropaenic sepsis
4. In combination therapy for neonatal sepsis (pen/fluclox)
5. In combination therapy for P. aeruginosa infection (Cf)
6. In combination therapy for S. aureus

25

Aminoglycosides: Side effects

7. Nephrotosicity (reversible)
8. Otototoxicity (irreversible)

26

Glycopeptides Example

Vancomycin

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Glycopeptides Absorption

Intravenous hospital only, wide use to treat multi resistant Gram positive infection, especially MRSA

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Glycopeptides Action

Inhibiting cross linking of bacterial cell wall

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Glycopeptides Resistance

Rare except in Enterococci and due to altered target side (enterococci, Staphylococci) and permeability (Staphylococci)

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Glycopeptides Excretion

Renal

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Glycopeptides Metabolism

None

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Glycopeptides Absorption note

Used for C.diff as although it has no oral bioavailabiity this doesn’t matter as it can target the gut without being absorbed.

33

Glycopeptides Side effects

Nephrotoxicity (around 10%) increased by use of other
Nephrotoxicity agents (gentamicin, frusemide)
Otoxicity very rare
Red man syndrome 9vancomycin) – histamine release mean the does is given too quickly
Thrombocytopenia (teicoplanin in big doses)

34

Glycopeptides Requires

Therapeutic drug monitoring

35

Glycopeptides Spectrum

Broad Spectrum: Active against nearly all gram positive bacteria, expecially multi resistant strains.
Not activie against Gram negative bacteria

36

Glycopeptides Indications

• MRSA infection
• Clostridium difficle associated diarrhoea (CDAD) as 2st line treatment
• Multiresistant Gram positive infection i.e. coagulase negative Staphylococci, Cornebacteria, Enterococci
• Prosthetic infection (Line, joint tc
• Penicillin allergy

37

Macrolides: Examples

Erythromycin/clarithromycin

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Macrolides: Absorption

• IV and po agents widely used in hospital and community to treat lower respiratory tract infection and in penicillin allergy.
• Reasonable bioavailability
• Good oral absorption

39

Macrolides: Action

Inhibition of protein synthesis at ribosome

40

Macrolides: Resistance

Common, due to target modification

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Macrolides: Distribution

Good tissue penetration

42

Macrolides: Excretion

Biliary and renal

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Macrolides: Side effects

Nausea and GI upset, especially erythromycin (pharmacological effect on stomach motility)

44

Macrolides: Spectrum

1. Active against gram positive organism i.e. s. aureus ( not MRSA), Streptococci, resistance 10-20%
2. Active against atypical respiratory pathogens legionella, Mycoplasma, chlamydia
3. No activity against Gram negatives except for campylobacter

45

Macrolides: Indications

• Skin/soft tissue infection if penicillin allergic
• Community acquired pneumonia
• Campylobacter infection
• H. Pylori
• (Staph and strep)

46

Tetracycines: Examples

Minocycline
Doxycycline

47

Tetracycines: Used in

Primary Care to treata acne
In hospital as oral therapy for MRSA

48

Tetracycines: Action

Inhibits synthesis at ribosome

49

Tetracycines: Resistance

Relatively common due to efflux pumps and target site modification

50

Tetracycines: Contraindicated in children as

Concentrated in bones/teeth, bind to calcium

51

Tetracycines: Absorption

Only orally

52

Metronidazole: Absorption

Good bioavailability
Available as iv/po

53

Metronidazole: Widely used to

Treat anaerobic infection

54

Metronidazole: Action

Disrupts DNA

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Metronidazole: Distribution

Wide tissue distribution

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Metronidazole: Resistance

Very rare in anaerobes

57

Metronidazole: Safety concerns

Early pregnancy
Disulphuram-like reaction with alcohol, rare peripheral neuropathy on long therapy (Augments hangover)

58

Trimethoprim: Absorption

Po/Iv only with sulphamethoxazole (co-trimoxazole) to treat PCP

59

Trimethoprim: Used to treat

Uncomplicated UTI

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Trimethoprim: Action

Inhibits Folate metabolism by inhibition of dihydrofolate reductase

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Trimethoprim: Resistance

By over production or modification target enzyme enzyme (20% E.coli)
Renal excretion

62

Linezolid Which forms is available for clinical use

Oxazolidinase

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Linezolid Active against

A wide range of gram positive bacteria including multi-resistant strains (MRSA, VRE)

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Linezolid Absorption

Good bioavailability

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Linezolid Penetration

Moderate/good tissue distribution

66

Linezolid Excretion/metabolism

None enzymatic degradation
Breakdown products renally excreted

67

Daptomycin: Absorption

Only lipopeptide antibiotic available. Iv only.

68

Daptomycin: Active against

A wide range of gram positive bacteria including multi resistant strains (MRSA, VRE)

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Daptomycin: Absorption

Poor oral absorption
IV only

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Daptomycin: Exrection

Renal

71

Daptomycin: Penetration

Poor lung penetration

72

Daptomycin: Toxicity

Muscle toxicity

73

Daptomycin: Second line for

Gram positive infection

74

Daptomycin: Not suitable for

Use in lung infection

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