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Antibacterial Drugs (Antifungals (fungal infections (Deep/systemic mycoses…

- - - - Cephalosporins
      - contatin a beta-lactam ring and thiozlidine ring,
        which need to be intact for the antibiotic activity
      - their structure resembles that of D-alanine, taking its binding site at Transpeptidase and thus inhibiting transpeptidation, an essential process for cellular-wall synthesis
      - some bacteria express Beta-lactamase, an enzyme
        that breaks the beta-lactam ring, providing them
        with immunity to beta-lactam antibiotics
      - Synthetic Beta-Lactams
      - Side Effects
        
        Hypertension - degradation products of penicilins act as haptens on host protein to evoke an immune response
        
        broad spectrum types given orally can alter gut flora, cause GI disturbances (diarrhoea) and present a risk of superinfection
      - Penicillins
      - Clavolanic Acid -taken with beta-lactams
    - - inhibits the transglycosylation reaction (binding to precursors) in the bacterial cell wall synthesis, as well as some other glycosylation reactions in eukaryotic cell (cannot use large doses)
      - bactericidal activity
      - cannot be broken down by B-lactamases
      - reserved for
        
        penicillin and cephalophorin sensitive individuals
        
        methicillin-resistant Staphylococcus Aureus infections
        
        superinfection of the bowel by Clostridium difficile
    - - amphipathic, cationic detergents
      - directly disrupt the gram-negative bacterial membranes
      - only topical application - eye and skin infections
    - - Isoniazid
        
        inhibits the synthesis of Mycolic Acid,
        an essential constituent of Mycobacterial cell-wall
        
        Bacteriostatic normally, but bacteriocidal in rapid bacterial division
        
        first line drug against tuberculosis
      - Ethambutol
        
        inhibits incorporation of mycolic acid into Mycobacterial cell-wall
        
        very specific action against Mycobacteria
        
        effective anti-tuberculotic drug, especially against isoniazid- and streptomycin-resistant strains
        
        penetrates into the CSF
  - - - Structural analogues of p-Aminobenzoic Acid
      - inhibit the first enzyme (DHO) in Folic Acid synthesis
    - - Structural analogues of the Pteridine
      - inhibit the second enzyme (FH2-Reductase)
        in Folic Acid synthesis
    - - structurally and mechanistically related to sulphonamides
      - act additionally on Mycobacteria
      - most important drugs against leprosy
      - Sulfone, Dapsone
    - - inhibit the activity of Topoisomerase II (Gyrase),
        preventing supercoiling of bacterial DNA
      - bactericidal
      - broad spectrum of activity
    - - inhibit RNA prokaryotic polymerase
      - bacteriostatic broad spectrum activity
      - used in combination with isoniazid and
        ethambutol against tuberculosis and leprosy
  - - - Bacteriostatic
      - absorbed orally, but complex with metal ions, so need to be administered without anything that contains them
      - first choice for infections with intracellular parasites
      - prevent binding of tRNA-AA to 30S subunit
    - - extremely polar - not absorbed orally
      - bacteriocidal
      - used in life-threatening cases of Gram -ve infections
      - prevent Codon-Anticodon recognition of tRNA and mRNA, resulting in the formation of malfunctioning proteins
    - - Bacteriostatic
      - excellent absorption, including CNS
      - use limited to life-threatening infections of respiratory tract, ear, sinuses, meninges where there is resistance to other drugs
      - binds to 50S subunits preventing the formation of bond
        between the consecutive AAs (blocks chain elongation)
    - - Bacteriocidal or Bacteristatic
      - well abosrbed but not to the CNS
      - used to treat pneumonia
      - bind to 50S subunit to prevent translocation of the ribosome
  - - - Anti anaerobic bacteria,
        Anti-protozoal and anti-amoebiasis
      - accept electrons from ETC only at sufficiently low electropotential, exhibited in bacteria but not in human cells
      - accepting electrons reduces the molecule
        into a Ferridoxin, which is toxic to DNA
        introducing mutations and reducing replication
      - Metronidazole
- - - - 50% peptidoglycan
      - 45% acidic polymer (negatively charged)
      - 5% proteins and polysacharides