Antibiotics Flashcards
What is bacteriacidal
Kills bacteria, reduces bacterial load
What is bacteriostatic
Inhibit growth and reproduction of bacteria
What are the β - lactams antibiotics
Cephalosporin
•Cefalexin •Cefuroxime •Cefotaxime •Ceftriaxone
Carbapenem
•Meropenem •Imipenem •Doripenem •Ertapenem
Penicillin
Narrow Spectrum
•Benzylpenicillin (Penicillin G) •Phenoxymethylpenicillin (Pen V) •Flucloxacillin
Broad Spectrum
•Amoxicillin/Co-amoxiclav •Ampicillin •Piperacillin with Tazobactam (Tazocin)
Beta lactams mechanism of action
They cause the osmotic pressure inside the bacterium to increase until they burst
spectrum of activity
• Very wide • Gram positive and negative bacteria • Anaerobes • Spectrum of activity depends on the agent and/or
its group
Resistance to beta lactams
ß-Lactamase
Cephalosporinase
Carbapenemase
How does aminoglycoside work
Inhibit bacterial protein synthesis by irreversibly binding to 30S ribosomal unit
Adverse effects of aminoglycosides
Nephrotoxicity
• Direct proximal tubular damage - reversible if caught early
• Risk factors: High troughs, prolonged duration of therapy, underlying renal
dysfunction, concomitant nephrotoxins
Ototoxicity
• 8th cranial nerve damage – irreversible vestibular and auditory toxicity
• Vestibular: dizziness, vertigo, ataxia • Auditory: tinnitus, decreased hearing • Serum levels do NOT reflect ototoxicity
Neuromuscular paralysis
• Can occur after rapid IV infusion especially with;
• Myasthenia gravis • Concurrent use of succinylcholine during anaesthesia
Examples of macrolides
• Clarithromycin • Erythromycin • Azithromycin
Macrolide clinical use
Gram Positive organisms
Cellulitis/Skin and soft tissue
• Beta haemolytic streptococci • Staphylococcus aureus
• Penicillin Allergy
Intra-cellular organisms
• Chlamydia • Gonococcus
Examples of fluoroquinolones
Ciprofloxacin Levofloxacin Moxafloxacin
Mechanism of action of fluoroquinolones
Relaxation of supercoiled DNA before replication
Summary of fluoroquinolones
• Wide range of activity against Gram positive and negative bacteria
• Do NOT cover streptococci or anaerobes
• Sepsis from intra-abdominal and renal source eg Gram negative bacilli
• UTI (eg. E. coli)
• Very good tissue penetration
• Excellent oral bioavailability
• Fluoroquinolone-associated tendon ruptures are a recognized complication and other
severe collagen-associated adverse events may also be possible
Examples of tetracyclines
•Tetracycline •Doxycycline
Mechanism of action of tetracycline
• Inhibit protein synthesis
• Bind reversibly to bacterial 30S ribosomal subunits and prevent binding of tRNA and hence polypeptide synthesis
• Bacteriostatic
