eLFH - Antimicrobial agents Flashcards
Classification of bacteria
Gram stain
Morphology (shape)
Relationship with oxygen (aerobes or anaerobes)
Gram positive bacteria features and appearance
Retain crystal violet stain in their thick outer peptidoglycan wall
Appear blue / violet
Gram negative bacteria features and appearance
Do not have outer peptidoglycan wall
Therefore don’t stain with crystal violet
Instead stain with safarin red counter stain and appear red / pink
Bacterial morphology classification
Cocci - spheres
Bacilli - rods
Spirilla - spirals
Gram positive bacteria tree
Gram negative bacteria tree
Bacteria responsible for Diphtheria
Corynebacterium
Aerobic bacteria definition
Use O2 for metabolism
Obligate anaerobes can only survive if O2 present
Anaerobic bacteria definition
Metabolise in absence of O2
Obligate anaerobes cannot survive in presence of O2
(lack enzymes to detoxify O2)
Facultative anaerobic bacteria definition
Can survive with or without O2
If given choice, prefer O2 as more efficient metabolism
Obligate anaerobic bacteria examples
Bacteroides
Clostridium
Three mechanisms of action of antibacterials
Actions on cell wall synthesis
Inhibition of protein synthesis
Inhibition of nucleic acid synthesis
Actions on cell wall synthesis mechanisms
Cell wall synthesis inhibitors
Cell wall integrity inhibitors
Cell wall synthesis inhibitor examples
Glycopeptides
Cell wall integrity inhibitor examples
Beta lactams
Inhibition of protein synthesis mechanisms
Ribosome 50s subunit inhibitors
Ribosome 30s subunit inhibitors
Ribosome 50s subunit inhibitor examples
Macrolides
Lincosamides
Chloramphenicol
Ribosome 30s subunit inhibitor examples
Tetracyclines
Aminoglycosides
Inhibition of nucleic acid synthesis mechanisms
DNA synthesis inhibitor
DNA gyrase inhibitor
DNA dependent RNA polymerase inhibitor
Folic acid metabolism inhibitor
DNA synthesis inhibitor examples
Nitroimidazoles
DNA gyrase inhibitor examples
Quinolones
DNA dependent RNA polymerase inhibitor examples
Rifampicin
Folic acid metabolism inhibitor examples
Diaminopyrimidines (e.g. trimethoprim)
Mechanism by which beta lactams reduce cell wall integrity
Inhibit enzymes which cross link the peptidoglycan chains of the cell wall
Beta lactam abx examples
Penicillins
Cephalosporins
Carbapenems
Monobactems
Mechanism by which glycopeptides inhibit cell wall synthesis
Bind to terminal residues of growing peptidoglycan chains - prevents formation of cross links
Glycopeptide abx examples
Vancomycin
Teicoplanin
Which abx classes are bacteriostatic rather than bactericidal
All abx which inhibit protein synthesis
Trimethoprim
Macrolides specific mechanism of action
Bind to 50s ribosome subunit and inhibits peptide chain translocation
Macrolide abx examples
Erythromycin
Clarithromycin
Azithromycin
Lincosamide specific mechanism of action
Disrupts 50s subunit to inhibit protein synthesis
Lincosamide abx examples
Clindamycin
Chloramphenicol specific mechanism of action
Inhibits peptidyl transferase activity of 50s subunit
Tetracycline specific mechanism of action
Binds to 30s subunit
Inhibits binding of aminoacyl-tRNA
Tetracycline abx examples
Doxycycline
Lymecycline
Aminoglycoside specific mechanism of action
Binds to 30s subunit
Causes misreading of mRNA
Aminoglycoside abx examples
Gentamicin
Amikacin
Neomycin
Streptomycin
Diaminopyrimidines specific mechanism of action
Inhibitor of dihydrofolate reductase
Needed for purine / pyrimidine synthesis
Diaminopyrimidine abx examples
Trimethoprim
Quinolones specific mechanism of action
Inhibits DNA gyrase
This enzyme usually compresses DNA into super coils