antibiotic therapy Flashcards
Antibiotics:
a drug used to treat or prevent infection caused by microorganisms
Bacteriostatic:
inhibit growth of bacteria
Bactericidal:
kill bacteria
Antibiotics that act on the bacterial cell wall
Inhibit cell wall synthesis by preventing cross linking of peptidoglycan - bactericidal
describe Penicillins e.g. flucloxacillin, amoxicillin
- β lactam
- Very few side effects
- Range from narrow to broad spectrum
- Excreted (rapidly) via kidneys
- Safe in pregnancy
describe Cephalosporins e.g. cefaclor, cefadroxil and cefalexin
Modified β lactam
Excreted via kidneys and urine
Safe in pregnancy
describe Glycopeptides e.g. vancomycin
- Not absorbed when given orally - have to be administered IV
- Side effects: vancomycin damages kidneys, occasionally causes ‘red man syndrome’ (allergy)
describe Antibiotics that inhibit protein synthesis
Attach to bacterial ribosomes
Usually protein synthesis can resume when antibiotic is removed - bacteriostatic
Exception: aminoglycosides - binding to ribosome is lethal
describe Macrolides e.g. erythromycin, azithromycin and clarithromycin
- Excreted via liver, biliary tract and into the gut
- Lipophilic - easily pass through cell membranes
- Useful for infections where bacteria ‘hide’ in host cells
- Erythromycin is safe in pregnancy (others have not been trialed)
describe Aminoglycosides e.g. gentamicin
Must be given IV
Active mainly against Gram-negative aerobic organisms
Excreted in urine
Side effects: kidney damage, deafness/dizziness
decisive clindamcyin
2nd line against serious Staphylococcal and Streptococcal infection, particularly in penicillin-allergic patients
-Also active against ‘true’ anaerobes
what is Chloramphenicol used for
topical eye infections
Tetracyclines
- Side effects - permanent staining of teeth (and bones) in children under 12
- All excreted via liver and biliary system
what Antibiotics can act on bacterial DNA
Metronidazole
describe Metronidazole
Oral, IV
Break strands of bacterial DNA
Used for infections by ‘true’ anaerobes and some infections by protozoa
Interacts with alcohol
Trimethoprim
Inhibits bacterial folic acid synthesis
Fluoroquinolones e.g. ciprofloxacin, levofloxacin
- Interact with topoisomerases – bacteria can no longer replicate
- Bactericidal
- Use is severely restricted - risk of C. difficile
- Only antibiotics that can be given orally to treat Pseudomonas
- Side effects: weakens tendons, may cause joint damage in young children, may cause seizures
general side effects
nausea, vomiting, diarrhoea, rashes, Candida infection
Penicillins side effect
hypersensitivity/skin reactions
Flucloxacillin and co-amoxiclav side effect
cholestatic jaundice
Clindamycin, cephalosporins and quinolones side effect
C. difficile colitis
Macrolides side effect
GI disturbances, hepatitis, Q-T interva
Quiolones side effect
Q-T interval, convulsions, tendonitis
Aminoglycosides/glycopeptides side effect
nephrotoxicity/ototoxicity
