mechanisms of action of antibiotics Flashcards
What are the three ways antibiotics may kill or inhibit bacteria?
- Inhibition of cell wall synthesis
- Inhibition of protein synthesis
- Inhibition of nucleic acid synthesis
Give two examples of groups of drugs which inhibit cell wall synthesis
Penicillins and cephalosporins
Give two examples of drugs which inhibit protein synthesis
Gentamicin and erythromycin
Give two examples of drugs which inhibit nucleic acid synthesis
trimethroprim and ciprofloxacin
What do beta lactam antibiotics do?
Inhibit cell wall synthesis
by inhibiting the enzymes responsible for cross-linking the carbohydrate chains for peptidoglycan synthesis
What are PBPs?
Penicillin binding proteins
Once the beta lactam antibiotics have disrupted peptidoglycan synthesis, how is the bacteria finally killed?
By autolytic enzymes
Penicillins and cephalosporins are what type of antibiotics?
Beta-lactam antibiotics
What type of drugs act of cell wall synthesis at a stage prior to beta-lactams, inhibiting assembly of a peptidoglycan precursor?
Glycopeptides
Which two glygopeptide antibiotics are in common clinical usage?
Vancomycin and teicoplanin
Do glycopeptides act on gram positive bacteria only, gram negative bacteria only or both?
Gram positive only
Which route of admission do glycopeptides take?
Parenterally as not absorbed from the GI tract
Which glycopeptide is toxic?
Vancomycin
Give an example of an aminoglycoside
gentamicin
What organisms are sensitive to gentamicin?
Gram negative (and Staphylococci)
Is gentamicin toxic?
yes
What type of antibiotics are useful alternatives to penicillins in treatment of gram positive infections in patients who are penicillin allergic?
Macrolides
Which two drugs are used for serious infection, MRSA in particular, which inhibit protein synthesis?
Linezolid and Daptomycin
What is the name of the combined drug of Trimethroprim and Sulphamethoxazole, which inhibits purine synthesis?
Co-trimoxazole
What is trimethroprim commonly used in the treatment of?
UTIs
What type of bacteria is Ciprofloxacin (nucleic acid synthesis inhibitor) particularly effective against?
Gram negative
Why can Ciprofloxacin not be used in children?
There is a danger of interference with cartilage growth
How can Ciprofloxacin be administered?
Orally or parenterally
