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• antibiotics 


  antimicrobial drugs used to treat bacterial infections
• antibiotic 


  a antimicrobial agent that kills bacteria
• anti fungals are harder to develop as fungi are eukaryotes like humans and have similar processes
• why group a strep sore throat needs antibiotics 


  not serious but may lead to rheumatic heart disease or complications
• indications for antibiotic therapy

  1 - threat a bacterial infection (severe, won't resolve) 2 - prevent bacterial infection (surgical prophylaxis) 3 - mixed superinfections
• antimicrobial stewardship 


  appropriate use of antimicrobials through 5 Rs, want to prevent drug resistance (includes use in human, vet medicine, agriculture)
• 5 R's 


  right diagnosis, drug, dose, duration, de escalation
• broad spectrum antibiotics 


  active against lots of bacteria (gram pos and neg), used for empiric therapy, lead to spread of MDR bacteria
• broad spectrum example


  amoxicillin for strep A
• narrow spectrum antibiotics 


  active against fewer, specific bacteria, more targeted so don't select for resistance (doesn't kill as many gut bacteria)
• narrow spectrum example


  penicillin for strep A
• mechanisms of antibiotic resistance

  prevent antibiotic from reaching its target, modify or bypass the target of antibiotic
• some bacteria are naturally resistant to certain antibiotics e.g bacteria with no cell walls resistant to B-lactams
• how stop antibiotic from reaching its target (for resistance)

  pump out/efflux the antibiotic, decrease permeability of bacterial cell membrane (mutate porin channels), bacterial enzymes inactive antibiotics, bacterial enzymes modify antibiotics to prevent binding target
• amino glycoside modifying enzymes

  add chemical groups methyl or acetyl to antibiotic to stop it reaching its target
• how modify or bypass target of antibiotic 


  camouflage target by changing structure in the bacteria or bypass target
• mecA


  a resistance gene s.aureus can acquire which produces a new PBP with a low affinity for B-lactam antibiotics (target is trying to target PBPs)
• syndromic management 


  term for when broad spectrum antibiotics used to treat infections where don't know exact bacterium cause
• problem with syndromic management

  one microorganism can cause infection at many different sites in body and an infection at a particular site can be caused by many microorganisms
• for pneumonia need to make antibiotic treatment decision before getting results of testing = syndromic management
• infectious syndromes 


  infection of a particular body site e.g lower respiratory tract set of symptoms = syndrome
• how are infectious syndromes treated

  syndromic approach - don't know actual cause so treat most common cause = empiric therapy
• empiric therapy 


  knowing most common causes of a clinical syndrome allow initial (broad spectrum) antibiotic therapy
• directed therapy 


  specific causative organism identified in microbiology lab can target therapy with narrow spectrum antibiotics to treat
• why is it hard to treat infections in people who have had chemotherapy

  antibiotics require support from host immune system to eradicate infection
• antagonistic antibiotics 


  target the same metabolic pathway, they compete for binding
• synergistic antibiotics 


  target different pathways, greater effect
• bacteria susceptibility to antibiotics varies according to their

  metabolic activity (activity dividing = more susceptible) and local environment (biofilm = more resistant)
• macrolides example


  erythromycin
• tetracyclines example 


  tetracycline
• sulfonamides example


  sulfanilamide
• quinolones example


  ciprofloxacin
• glycopeptides example 


  vancomycin
• aminoglycosides example


  streptomycin
• B-lactams example 


  penicillins such as amoxicillin
• macolides mode of action

  inhibit protein synthesis by bacteria, sometimes leads to cell death
• tetracylines mode of action

  inhibits bacteria protein synthesis to prevent growth
• sulfonamides mode of action

  prevent growth of bacteria, inhibit folate synthesis
• quinolones mode of action


  inhibit DNA supercoiling by inhibiting DNA gyrase enzyme (bacterial cell can't package DNA)
• glycopeptides mode of action

  inhibits peptidoglycan synthesis (NAM-NAG polymerisation)