Flashcards in Microbiology Antibiotics 2 Deck (74)
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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
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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)
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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
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Spectrum – moxifloxacin: Target
• Much improved activity versus Staphylococci and Streptococci
• Poor activity vs. P.aeruginosa, better activity against anaerobes
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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)
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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
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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
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Aminoglycosides: Side effects
7. Nephrotosicity (reversible)
8. Otototoxicity (irreversible)
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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.
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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)
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Glycopeptides Requires
Therapeutic drug monitoring
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Glycopeptides Spectrum
Broad Spectrum: Active against nearly all gram positive bacteria, expecially multi resistant strains.
Not activie against Gram negative bacteria
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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
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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
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Macrolides: Action
Inhibition of protein synthesis at ribosome
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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)
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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
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Macrolides: Indications
• Skin/soft tissue infection if penicillin allergic
• Community acquired pneumonia
• Campylobacter infection
• H. Pylori
• (Staph and strep)
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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
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Tetracycines: Absorption
Only orally
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Metronidazole: Absorption
Good bioavailability
Available as iv/po
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Metronidazole: Widely used to
Treat anaerobic infection
54
Metronidazole: Action
Disrupts DNA
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Metronidazole: Distribution
Wide tissue distribution
56
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
60
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
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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
65
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
70
Daptomycin: Exrection
Renal
71
Daptomycin: Penetration
Poor lung penetration
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Daptomycin: Toxicity
Muscle toxicity
73
Daptomycin: Second line for
Gram positive infection
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