Flashcards in Intro to Antibacterial agents Deck (31):
What are Antibiotics?
Chemical products of MICROBES that inhibit or kills other organisms
What are antimicrobial agents?
Encompasses antibiotics - synthetic/semi -synthetic with similar effect to antibiotics
Bacteriostatic - inhibits bacteria growth - protein synthesis inhibitor
Bactericidal - kills bacteria - cell wall-active agents
Minimum Inhibitory concentration
Minimum concentration of antibiotic/antimicrobial agent at which visible growth is inhibited
Synergy - activity of 2 antimicrobials are greater than if each one was given separately
Antagonism - activity of one animicrobial diminishes activity of other
Indifference - activity of antimicrobials is unchanged if given together
Interrupt/inhibit critical intracellular processes/structures e.g. enzymes, molecules, structures
Develop microbial so to target organisms without harming human host
Main constituent of Bacterial cell wall (gram positive and negative)
- no cell wall in animal cells -> good for selective toxicity!
What are the main inhibitors of cell wall synthesisers?
- Beta Lactams e.g. penecillin
Mechanism of Beta lactams
Beta lactam ring - blocks cell wall synthesis by blocking 'penicillin binding protein' (which constructs cel bacterial wall (NAG and NAM), not binds penicillin!)
Major classes of Beta lactams
Penecillin (-llin) - e.g. amoxicillin, flucloxacillin (for staph aureus)
Cephasporins e.g. cefuroxime, ceftazidime - broad spectrum (gram negative
Carbapenems e.g. meropenem, imipenem - EXTREMELY broad spectrum
Monobactams - Aztreonam - gram negative only (
Mechanisms of Glycopeptides
Prevents cross linking of peptideoglycans by binding directly to terminal D-Alanyl-D-Alanine on NAM pentapeptides
Example of Glycopeptides
What class of bacteria are cell wall synthesis inhibitors ineffective?
Gram negative bacteria - unable to penetrate outer membrane porins
ONLY EFFECTS GRAM POSITIVE
Where does translation of RNA take place?
What constitutes a bacterial ribosome?
50s (large) and 30s (small) subunit; combine too form 70s initiation complex
Protein synthesis inhibitors - blocks 50s?
Macroslides, lincosamides and streptogramins (MLS)
- Linezolid - inhibits initiation of protein synthesis (50S) and assembly of initiation complex (70S)
Protein synthesis inhibitors - mechanism?
Bind to ribosome subunits, preventing translation
Protein synthesis inhibitor classes blocks 30S?
- Aminoglycosides e.g. gentamicin
- Tetracycline e.g. tetracycline
What classes inhibits DNA synthesis?
Trimethoprim - inhibits folate synthesis
Quinolone/Fluroquinolones - inhibit DNA gyrate and topoisomerase
RNA synthesis inhibitor?
What do RNA synthesis inhibitors do?
RNA polymerase inhibitor and stops mRNA synthesis
What do plasma membrane agents do?
Destroy cell membrane
Main types of plasma membrane agents for both gram positive and negative bacteria?
Gram + = daptomycin (e.g. cyclic lipopeptides look like a frying pan!)
Gram- = colistin
Adverse effects of antibiotics?
- Nausea, vomiting, headache, rash etc
- generation of antibiotic resistance
- fungal infection (superficial and invasive candidiasis)
- C. diff infection
Name some specific antibiotic adverse effects
Beta lactams - allergies
-Amino glycosides - renal impairment
-Linezoid - bone marrow depression
What beta lactam antibiotic (and why) is suitable for people with penicillin?
Aztreonam - because it lacks bicyclic nucleus
4 most common precipitating antibiotics for C. Diff?
- C - amoxiclav
Pharmacodynamic considerations - what are the time and concentration considerations?
How long and how much agents exceed minimum inhibitory concentration