Question | Answer |
5 major groups of antibiotics (and the antibiotic that doesn't fit) | Penicillins, cephalosporins, macrolides, tetracyclines, aminoglycosides, (metronidazole) |
Beta-lactams include | Penicillins, cephalosporins, carbapenems, mono-bactams |
Main causes of infection and gram status | Staph/Strep/Enterococci gram +ve, enteric gram -ve, Psuedomonas gram -ve, anaerobes gram +ve or -ve, intracellular/no cell wall |
Development of penicillins and cephalosproins | Increased spectrum and activity for gram -ve bacteria\ |
Penicillin characteristics and uses | Narrow, gram +ve (mainly Strep.), exceptions e.g. Neisseria susceptible |
Amp/Amoxycillin characteristics and uses | Resistance problems, gram +ve/-ve |
Flucloxacillin characteristics and uses | More stable to beta-lactamses, Staph. aureus |
Piperacillin charactersitics and uses | Extended spectrum, gram -ves, Pseudomonas |
Examples of combinations of Penicillins and beta-lactamase inhibitors | Co-amoxyclav (augmentin), tazocin |
Co-amoxyclav is a combination of | Amoxycillin and clavulanic acid |
Tazocin is a combination of | Piperacillin and tazobactam |
Carbepenems examples | Imipenem, meropenem |
Carbepenems characteristics and uses | Extremely broad spectrum (so inhibit normal microflora), uses for mixed and serious infections in hospital patients |
Monobactam example | Aztreonam |
Monobactam uses | Limited to gram +ves, useful for carbapenemase producers |
Cephalosporins characteristics and uses | More beta-lactamase stable, wider range of microbes, poor activity against Enterococcus |
Antibacterial activity of beta-lactams depends on | Time spent above MIC |
Probenicid mechanism and use | Competitive inhibition of kidney's organic ion transporter --> decrease excretion of some drugs including cephalosporins |
Adverse reactions to beta-lactams | allergic, GI (diarrhoea/antibiotic associated colitis especially in co-amoxyclav, yeast overgrowth), rare (biliary sludging in ceftriaxone, nephorotixicity in penicillin, inhibition of blood clotthin in cefamandole, cefotetan) |
Aminoglycoside characteristics | Low TI, potentially toxic (nephrotoxicity, ototoxicity), adaptive resistance (if bacteria not killed straight away), must be IV, synergy with beta-lactams, post antibiotic effect |
Aminoglycoside uses | For serious gram -ve infection, Staph. aureus, poor activity against Streps. |
Aminoglycoside examples and specific uses | gentamicin, tobramycin (Psuedonomonas), amikacin (for gentamicin resistant) |
Anibacterial activity of aminoglycosides depends on | Height of peak of antibiotic concentration |
Which antibiotic is the once-daily regime used for and why | Aminoglycosides because they have concentration dependent killing, post antibiotic effect, and the regime is less nephrotoxic (even with renal insufficiency, levels will fall enough before next dose) |
Macrolides/azalides examples | Erythromycin, roxithromycin, clarithromycin, azithromycin (last 3 have longer plasma half-lifes) |
Macrolides/azalides uses | gram +ve and intracellular, RTIs, STIs, patients allergic to penicillin, some mycobacteria, use in biofilm infections? (prevent secretion of matrix), no activity against gram -ve enterics or Pseudomonas |
Quinolones/fluoroquinolones characteristics | Excellent absorption/bioavailability given orally, newer ones very wide spectrum, resistance problems |
Quinolones/fluoroquinolones uses | Excellent activity against gram -ve aerobic rods |
Quinolones/fluoroquinolones examples and specific uses | norfloxacin for UTIs, ciprofloxacin for GTIs, moxifloxacin for RTIs (extended spectrum including gram +ves) |
Tetracycline characteristics and uses | Very broad spectrum, chronic RTIs, chlamydia (both intracellular), not in children/pregnancy |
Tetracycline example | doxycyline |
Treatment for uncomplicated UTIs | trimethoprim, nitrofurantoin |
Treatment for anaerobes | metronidazole |
Problems with antibiotics | liberation of bacterial cell wall fragments (pro-inflammatory), side effects, allergy, resistance, antibiotic associated diarrhoea, antibiotic associated colitis (especially following clindamycin/chemotherapy for neoplasms) |