BIOMED SCIE Lecture 15 Antibiotics and Treatment

• Disk-Diffusion Method


  Identifying suitable antibiotics and MIC
• Synergism


  • Effect of two drugs together is greater than the effect of either alone
• Antagonism


  • Effect of two drugs together is less than the effect of either alone
• Augmentin


  Combination of potassium clavulanate (an inhibitor of penicillinase) combined with broad spectrum penicillin (Ampicillin)
• Antibiotic resistance mutations


  Can have other benefits
• Emergence of Resistance to Penicillin


  1. Gene for beta-lactamase (penicillinase) discovered before penicillin used in clinics

  2. Quickly emerges in S. aureus strains in 1940s as penicillin use becomes more widespread
• MRSA


  • Methicillin works by inhibiting the transpeptidase enzyme for S. aureus cell wall synthesis
  • MRSA use a different transpeptidase
  • When exposed to methicillin MRSA strains are thus more likely to survive and reproduce than susceptible strains
  • MRSA strains are now resistant to many antibiotics
• We have a limited number of families of antibiotics with a limited number of targets
• Over the past 70 years we have benefited from an age where we had a "silver bullet" to protect against bacterial infection
• The rise of antibiotic resistance suggests this age is coming to a swift end
• Teixobactin


  Discovery signals a new class of Antibiotics
• Ichip


  Opening new environments and new organisms with novel antibiotics
• Antibiotics affect a lot of bacteria, not just the pathogen being treated
• Affecting this diversity can upset the natural balance of the Microbiome and allow space for some opportunistic pathogens to take advantage
• Monoclonal Antibody therapy for Covid-19


  • Antibody cocktail targets spike protein
  • Casirivimab and Imdevimab "Regen-Cov"
• Antibiotics are microbial products aimed at other microbes which can be bacteriocidal or bacteriostatic
• Antimicrobial resistance a looming crisis
• Anti-Fungal drugs and toxic issues
• Anti-viral drugs to aim at inhibiting binding or disrupting the viral cycle
• [e-mail]: 'If you found Infection Biology interesting, Consider MICR20050 next year "Microbes in Medicine, Biotechnology and the Environment"'