B.2 Antibacterials

• What are antibiotics considered in medicine?

  One of the most successful therapeutic agents
• What prompted the US Surgeon General's statement in 1967?

  The success of antibiotics discovered in the 1945-1960 period
• What does the alarming rise of antibiotic resistance suggest?

  The 1967 statement was premature
• What is a global threat to human health?

  Antibiotic resistance
• Why are new antibiotics urgently required?

  Especially for Gram-negative bacteria
• What underpins modern medicine?

  Availability of effective antibiotics
• What is a major barrier to developing new antibiotics?

  Inability to cross the outer membrane
• What has the WHO warned about current antibiotics?

  They are not sufficiently innovative
• What is inevitable when using antibiotics?

  Resistance always emerges
• What are the three sources of antibiotics?

  Natural, semi-synthetic, synthetic
• How are antibiotics classified?

  Molecular structure, mechanism of action, spectrum
• What are the major classes of antibacterial agents?

  • Sulfonamides
  • Quinolones
  • β-Lactam
  • Aminoglycosides
  • Macrolides
  • Tetracyclines
  • Glycopeptides
• What is the simplest sulfa drug?

  PABA
• How do sulfonamides work?

  They interfere with folate biosynthesis
• Why are sulfonamides selectively toxic to bacteria?

  Bacteria synthesize their own folic acid
• What is the mode of action of β-lactams?

  Target bacterial penicillin-binding proteins
• What is a common side effect of β-lactams?

  Allergic reactions
• What do cephalosporins target?

  Broader spectrum of activity than penicillins
• What is the significance of carbapenems?

  Last resort antibiotics for resistant infections
• What is the mode of action of aminoglycosides?

  Inhibit protein synthesis by targeting 30S subunit
• What is the target of macrolides?

  50S subunit of the ribosome
• What is the mode of action of tetracyclines?

  Interfere with the 30S subunit of the ribosome
• What is the best-known glycopeptide antibiotic?

  Vancomycin
• How do glycopeptides inhibit bacterial wall synthesis?

  By binding to D-Ala-D-Ala
• What are the major mechanisms of resistance to β-lactams?

  • Hydrolysis by β-lactamases
  • Production of alternative PBPs (e.g., PBP2a)
  • Extended spectrum β-lactamases and carbapenemases
• What is the significance of ciprofloxacin?

  Widely used for Gram-negative infections
• What are the side effects associated with fluoroquinolones?

  Serious side effects including C. difficile infection
• What is the source of tetracyclines?

  Produced by several Streptomyces species
• What is the target of tigecycline?

  Broad-spectrum activity against Gram-positive and Gram-negative
• Why is tigecycline reserved for specific cases?

  Higher risk of death compared to other drugs
• What is the mode of action of glycopeptides?

  Inhibits bacterial wall synthesis
• What is the target spectrum of the ribosome inhibitors mentioned?

  Broad spectrum, affecting Gram-positive and Gram-negative
• What is the source of Oxytetracycline?

  Produced by Streptomyces rimosus
• What is a common use of Oxytetracycline?

  Treating acne caused by Propionbacterium acnes
• What is a significant issue with Oxytetracycline?

  High levels of resistance
• What is the source of Tigecycline?

  Semi-synthetic
• What is the risk associated with Tigecycline compared to other antibacterial drugs?

  Higher risk of death among patients
• How does the mode of action of Glycopeptides work?

  Inhibits bacterial wall synthesis by binding to D-Ala-D-Ala
• What type of bacteria do Glycopeptides primarily target?

  Most Gram-positive bacteria
• When was Vancomycin discovered?

  In 1953