Antibiotics

• What is the definition of "selective toxicity" in antibiotics?

  Selective toxicity refers to the ability of an antibiotic to target bacterial cells without harming mammalian cells.
• What are the broad categories of antimicrobials?

  • Bactericides
  • Bacteriostatic
  • Sporicidal
  • Virucidal
  • Antiprotozoal
  • Antifungal
  • Antihelmintic
• What is the purpose of phenotypic methods in determining antibiotic susceptibility?

  Phenotypic methods assess the effectiveness of antibiotics against bacteria in vitro.
• What are some early treatments for infections mentioned in the study material?

  Early treatments included oils, crude plant extracts, quinine for malaria, mercury for syphilis, and chaulmoogra oil for leprosy.
• What was Lister's contribution to treating wound infections?

  Lister used carbolic acid to treat wound infections.
• What was the efficacy of early treatments like mercury and chaulmoogra oil?

  These treatments had low efficacy and were damaging to healthy tissue.
• What were arsenicals used for in the 1900s?

  Arsenicals were used as antiprotozoal agents for schistosomiasis and syphilis.
• What are sulfa drugs known for?

  Sulfa drugs from the 1930s had a limited spectrum of activity.
• What is the role of glutaraldehyde in medical settings?

  Glutaraldehyde is a powerful disinfectant used for medical equipment.
• What is the difference between bactericidal and bacteriostatic agents?

  Bactericidal agents kill bacteria, while bacteriostatic agents inhibit their growth.
• Why are antibiotics given to a broad range of microbes?

  Antibiotics are designed to target and kill a wide variety of bacteria.

  
• What is the mechanism of action of triclosan?

  Triclosan targets multiple sites in the membrane and cytoplasm of bacteria.
• Why has triclosan been banned in some countries?

  Triclosan does not biodegrade and can contaminate water sources, exerting selective pressure on microbial environments.
• How do antibiotics achieve selective toxicity?

  Antibiotics affect targets found in bacterial cells that are not present in mammalian cells.
• How do bacteriostatic antibiotics treat infections?

  Bacteriostatic antibiotics inhibit bacterial reproduction, allowing the immune system to eliminate the bacteria.
• What species is used for the production of penicillin?

  Penicillium chrysogenum is the species used for penicillin production.
• What was the significance of Fleming's discovery of penicillin?

  Fleming discovered penicillin accidentally, which inhibited Staphylococcus aureus.
• What was Selman Waksman's contribution to antibiotics?

  Waksman discovered streptomycin, the first drug effective against tuberculosis.
• What does "serendipitous discovery" mean in the context of antibiotics?

  Serendipitous discovery refers to accidental findings that lead to significant breakthroughs, like Fleming's discovery of penicillin.
• What are the stages of how infections are established?

  1. Attachment to epithelial surface
  2. Penetration of epithelial surface
  3. Interference/avoidance of host defenses
  4. Multiplication in host tissue
  5. Damage of host tissue
• Why do most antibiotics target stage 4 of infection establishment?

  Most antibiotics target stage 4 to kill bacteria or slow their growth, allowing host defenses to regain control.

  
• Why are there more antibiotics that act on the cell wall than on nucleic acids?

  Bacterial cells have cell walls, while mammalian cells do not, allowing antibiotics to target bacteria without harming host cells.
• How can infection be managed by addressing stages 1 and 2 of the infection process?

  Infection can be managed through vaccination and probiotics to maintain healthy microbiota.
• Which antibiotics correspond to DNA replication processes?

  Quinolones and metronidazole correspond to DNA replication processes.
• What is the role of beta-lactams in antibiotic action?

  Beta-lactams affect the construction of peptide bridges in bacterial cell walls.

  
• What is the mechanism of action of glycopeptide antibiotics?

  Glycopeptide antibiotics bind to the growing peptidoglycan chain and prevent transglycosylation.

  
• Why is vancomycin considered an antibiotic of last resort?

  Vancomycin is often used as a last resort due to its potential for serious side effects and the emergence of resistant strains.
• How do bacteria develop resistance to vancomycin?

  Bacteria change the structure of the peptide bridge, preventing vancomycin from binding.

  
• What is the mechanism of action of beta-lactam antibiotics?

  Beta-lactam antibiotics bind to penicillin-binding proteins, inhibiting cross-links between peptidoglycan chains, leading to cell lysis.

  
• What are the different classes of beta-lactamases?

  Classes of beta-lactamases include penicillinases, extended-spectrum beta-lactamases (ESBLs), and cephalosporinases.
• What is the function of side chain variations in beta-lactams?

  Side chain variations enhance stability against enzymes that break down beta-lactams and reduce toxicity to the host.
• What infections are linked with extended-spectrum beta-lactamase (ESBL) producing organisms?

  Infections linked with ESBL-producing organisms include UTIs, hospital-acquired pneumonia, and sepsis.
• What is the role of beta-lactamase inhibitors?

  Beta-lactamase inhibitors bind to beta-lactamase enzymes, preventing them from breaking down beta-lactam antibiotics.

  
• What is co-amoxiclav?

  Co-amoxiclav is a combination of amoxicillin and clavulanic acid, used to inhibit beta-lactamase activity.

  
• How does clavulanic acid enhance the effectiveness of amoxicillin?

  Clavulanic acid has a higher affinity for beta-lactamase enzymes, allowing amoxicillin to remain active against bacteria.

  
• How does vancomycin differ from beta-lactams in its mechanism of action?

  Vancomycin binds to the sticky ends of peptide bridges, while beta-lactams bind to transpeptidase enzymes.

  
• In which infections can penicillin still be used effectively?

  Penicillin can be used effectively for infections like streptococcal pharyngitis, endocarditis, and syphilis.
• Why are there fewer antibiotics available for obligately parasitic bacteria?

  Obligately parasitic bacteria reside within host cells, making it more challenging for antibiotics to penetrate.
• What is the mechanism of action of polymyxins?

  Polymyxins disrupt the inner and outer cell membranes of gram-negative bacteria, causing cell lysis.

  
• What are the side effects associated with colistin use?

  Colistin can cause nephrotoxicity and neurotoxicity, especially in patients with renal function disorders.