MCB (Subject) / Antibiotics (Lesson)

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• Antibiotics - Interference with cell wall synthesis 1. b-lactams - bacterial cell wall  - penicillins - cephalosporins - carbapenems - monobactams  --> resistance by betalactamase (hydrolysis of antibiotics) 2. Glycopeptides - bind to the amino acids within the cell wall preventing the addition of new units to the peptidoglycan - vancomycin - teicoplanin
• Antibiotics protein synthesis inhibition 1. Antibiotics binding to the 50s subunit, preventing translation - Macrolides - Chloramphenicol - Clindamycin - Quinupristin-dalfopristin - Linezolid 2. Antibiotics binding to the 30s subunit, preventing translation - Aminoglycosidases - Tetracyclines 3. Antibiotics binding to bacterial isoleucyl-tRNA sythetase  - Muporicin
• Antibiotics - Interference with nucleic acid synthesis 1. Fluoroquinolones - Inhibit DNA synthesis  by blocking chromosome supercoiling  2. Rifampin - Inhibit RNA synthesis 
• Antibiotics - Disruption of bacterial membrane structure 1. Polymyxins 2. Doptomycin
• Antibiotics - Inhibition of metabolic pathways 1. Sulfonamides - competitive inhibitors of the enzyme dihydropteroate synthase (DHPS), an enzyme involved in folate synthesis 2. Folic acids analogues 3. Trimethoprim - inhibits bacterial enzyme dihydrofolate reductase  4. Cotrimoxazole - same as 3. 
• Mechanisms of resistance 1. Genetic events - mutations and resistance gene acquisition (transformation, conjugation, transduction) 2. Selection - eradication of susceptible populations and dominance of natural resistant (sub)populations 3. Dispersion - spread of resistant isolates (clones) or even resistant genes 

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