Antibiotics Flashcards
Name 3 important types of G +ve cocci
Staphylococci, Streptococci, Enterococci.
Name 2 important types of G -ve cocci
Neisseria Meningitidis, N. Gonorrhoea.
Name 5 important types of G +ve bacilli
Clostridia, Corynebacterium, Bacillus, Lactobacillus, Mycobacterium.
Name 4 important types of G -ve bacilli
E coli, Pseudomonas, salmonella, Haemophilus influenzae.
Name 2 important types of G -ve spirilla
Campylobacter and Helicobacter.
Which type of bacteria is Metronidazole particularly good against and in which context might it be given?
Anaerobes- prophylaxis for ‘dirty’ gut surgery.
Classify the pathogen “cryptococcus neoformans”.
Despite the name suggesting it’s a coccus bacteria, it’s actually a fungus. It may cause meningitis or blindness.
Suggest ways in which antibiotics may be classified.
Bactericidal or Bacteriostatic, Broad spectrum or narrow spectrum, the Target site, and the Chemical structure.
Which types of antibiotics affect cell wall synthesis?
Beta lactams and glycopeptides.
Which types of antibiotics affect protein synthesis?
Tetracyclines, aminoglycosides, macrolides.
Which types of antibiotics affect nucleic acid synthesis?
Quinolones, rifampicin.
Give a brief description of the mechanism of action of penicillin.
Inhibits Penicillin Binding Protein from forming the cross links in the cell wall.
Give a brief description of the mechanism of action of vancomycin.
Binds to the chains of the cell wall, preventing PBP from binding to form cross links between them.
Outline mechanisms of antibiotic resistance.
Microbe produces drug inactivating enzymes (e.g. Beta lactamases), the target of the antibiotic is altered, or the permeability of the wall is reduced so the drug can’t reach it’s target.
Outline mechanisms of resistance transfer.
Reproduction, or horizontal transfer via conjugation (direct), transduction (viral vector), or transformation (freely through the cell wall).
What type of antibiotic is penicillin and what type of bacteria is it mostly effective against?
Beta lactams- effective against G +ve cocci.
What type of antibiotic are cephalosporins and when might they be used?
Beta lactam. Ceftriaxone has good activity in the CSF- meningitis. However, there is general cause for concern about their association with C difficile.
What type of antibiotic are carbapenems and what type of bacteria are they mostly effective against? When might they be used?
Beta lactam. Broad spectrum, active against most G -ve bacteria, but resistance is developing. May be used in Sepsis.
What type of antibiotic is vancomycin and what type of bacteria is it mostly effective against?
Glycopeptide. G +ve, NOT absorbed by the gut, has a narrow therapeutic window so requires monitoring.
What type of antibiotic are tetra- and doxycycline and what type of bacteria are they mostly effective against?
Tetracyclines. Broad spectrum, useful for penicillin allergy, usually given for G +ve.
What type of antibiotic is gentamicin and what type of bacteria is it mostly effective against? When might they be used?
Aminoglycoside. Used vs G -ve, has good activity in blood and urine BUT may be nephrotoxic and damage the ears. Generally reserved for severe G-ve sepsis.
What type of antibiotic is erythromycin and what type of bacteria is it mostly effective against?
Macrolide. Good alternative to penicillin for mild G +ve infections.
What type of antibiotic is ciprofloxacin and what type of bacteria is it mostly effective against?
Quinolone. V active against G -ve, however there is increasing resistance from C diff.
What type of antibiotic is trimethoprim and how does it work, and when might it be used?
Antifolate DHFR inhibitor. Inhibits folic acid synthesis, which ultimately inhibits bacterial DNA synthesis. Used for UTI.
