Chemotherapy: Antibiotics Flashcards
D-cycloserine
Inhibits cell wall biosynthesis
Structural analogue of D-Ala; prevents synthesis of pentapeptide by inhibiting L-Ala racemase, D-Ala-D-Ala synthetase and D-Ala-D-Ala/ muramyl tripetide ligase
Fosfomycin
Used in treatment of?
Inhibits cell wall biosynthesis
Inhibits puruvyl transferase required for conversion of NAG into NAM
Treatment of UTI
Bacitracin
Active against Gram positive or gram negative?
Inhibits cell wall biosynthesis
Cyclic polypeptide
Forms a tight complex with Mg2+ and bactoprenol pyrophoasphate; inhibits dephosphorylation to bactoprenol phosphate (lipid carrier for NAM-NAG unit)
Active against Gram-positive bacteria
Penicillin
Inhibits cell wall biosynthesis
beta-lactam antibiotic
Inhibits peptidoglycan-crosslinking transpeptidase enzymes by covalent & irreversible binding as a pseudosubstrate.
Ampicillin
Inhibits cell wall biosynthesis
beta-lactam antibiotic
Inhibits peptidoglycan-crosslinking transpeptidase enzymes by covalent & irreversible binding as a pseudosubstrate.
Amoxicillin
Inhibits cell wall biosynthesis
beta-lactam antibiotic
Inhibits peptidoglycan-crosslinking transpeptidase enzymes by covalent & irreversible binding as a pseudosubstrate.
Methicillin
Inhibits cell wall biosynthesis
beta-lactam antibiotic
Inhibits peptidoglycan-crosslinking transpeptidase enzymes by covalent & irreversible binding as a pseudosubstrate.
Clavulanate
beta-lactamase inhibitor
Augmentin
Combination of amoxicillin and clavulanate
Vancomycin
Used to treat which bacteria?
Inhibits cell wall biosynthesis
Glycopeptide antibiotic
Binds D-Ala-D-Ala termini of the pentapeptide in peptidoglycan- preventing its cross-linking to another peptidoglycan strand.
Effective against clostridium difficile, used intravenously against gram positive cocci e.g enterococcus, staphylococcus
Isoniazid
Inhibits biosynthesis of mycolic acids in cell envelope of Mycobacterium Tuberculosis
Used in prevention and treatment of TB
Chloramphenicol
Uses?
Acts on protein synthesis
Blocks aminoacyl tRNA binding to 50S subunit of ribosome
V effective broad spectrum antibiotic but use restricted due to bone marrow suppression in some cases. Indicated in e.g meningitis
Tetracycline
Used against?
Side effects?
Acts on protein synthesis
Polyketide antibiotic
Binds to 16rRNA in 30S subunit of ribosome, inhibits mvt of amino-acyl tRNA into A site.
Effective against a wide range of bacteria, including mycoplasma and cholera.
Toxicity associated with binding of calcium in bones and teeth.
Erythromycin
Spectrum/ uses?
Acts on protein synthesis
14-membered macrolide antibiotic
Binds to 23SrRNA in 50S subunit, and blocks polypeptide exit tunnel.
Similar antibacterial spectrum as penicillin, used as second-line drug for patients allergic to penicillin.
Fusidic acid
Spectrum?
Acts on protein synthesis
Inhibits elongation factor G- and hence the movement of 30S subunit by one unit along the mRNA
Narrow spectrum, used against staphylococcal infections
Streptomycin
Side effects?
Used against?
Acts on protein synthesis
Aminoglycoside antibiotic
Target 30S subunit of ribosome & decrease fidelity of mRNA translation.
Exhibits nephrotoxicity and ototoxicity
Used against gram negative rods: e.g pseudomanas, proteus
Gentamycin
Side effects?
Used against?
Interaction with penicillin?
Acts on protein synthesis
Aminoglycoside antibiotic
Target 30S subunit of ribosome & decrease fidelity of mRNA translation.
Less nephrotoxicity & ototoxicity than streptomycin
Used vs gram -ve rods: e.g Pseudomanas, Proteus
Most streptococci (gram +ve) are resistant because cannot penetrate the cell
Synergistic effect against some streptococci with penicillin.
Ciprofloxacin
Uses?
Fluoroquinolone antibiotic
Inhibits type II DNA topoisomerases (DNA gyrase & topo IV)- hence inhibits changes in supercoiling required for replication & gene expression.
Used vs bacillus anthrax (anthrax infections), and in Pseudomonas infections where oral therapy is preferred- e.g respiratory tract infections in CF patients.
Rifampin
Uses?
Binds beta subunit of DNA-dependent RNA polymerase- inhibits initiation of RNA synthesis
Used vs mycobacterium
Daunomycin
Uses?
Planar polycyclic anthracycline antibiotic
Intercalates in dsDNA and causes local unwinding
Used as anticancer agent
Bleomycin
Metal-chelating glycopeptide antibiotic
Generates superoxide and hydroxyl radicals- causing single & double-stranded breaks in DNA
Mitomycin C
Aziridine-containing antibiotic
Alkylates & cross-links DNA, thereby preventing strand separation during DNA replication and transcription
Sulfamethoxazole
Acts as an antimetabolite
Sulfa drug
p-aminobenzoate analogue, competitively inhibits DHPS in biosynthesis of tetrahydrofolate (methyl carrier required for synthesis of dTMP)
Trimethoprim
Acts as antimetabolite
Inhibits DHFR in biosynthesis of tetrahydrofolate
Co-trimoxazole
Uses?
Combination of sulfamethoxazole and trimethoprim.
Used in AIDS patients with fungal Pneumocystis carinii infections
Withdrawn as routine anti-bacterial due to being implicated in cases of Steven-Johnson syndrome (severe & sometimes fatal allergic reaction)
Valinomycin
Targets membrane
Cyclic peptide antibiotic
Binds K+ and facilitates K+ diffusion across membrane
Granmicidin A
Targets membrane
Linear polypeptide antibiotic
Forms homodimeric complex that acts as an ion channel in the membrane
Polymixin
Targets membrane
Cationic detergent antibiotic containing cyclic peptide and hydrophobic tail
Binds to membrane & alters its ion permeability
Amphotericin B
Used against
Targets membrane
Polyene antifungal and antiparasitic drug
Forms pores in membrane by an ergosterol-dependent mechanism
Used against most systemic mycoses; active vs Cryptococcus, Candida, Aspergillus
Fluconazole
Used to treat
Targets membrane
Triazole antifungal drug
Inhibits ergosterol biosynthesis
Treatment of athletes foot & vaginal candidiasis
Miconazole
Triazole antifungal drug
Inhibits ergosterol biosynthesis
