Antibiotic Agents Against Bacterial Synthesis Flashcards
Identify the major classes of antibiotics that target the 30S ribosomal subunit (2). Briefly describe each.
Aminoglycosides - block initiation step, ribosomal translation step and cause mistranslation
Tetracyclines - block peptide elongation step @ 30S subunit
Identify the major classes of antibiotics that inhibit the 50S ribosomal subunit (4). Briefly describe each
- Macrolides - blocks ribosomal translocation step; bacteriostatic
- Clindamycin - blocks translocation step; bacteriostatic
- Streptogramins - block translocation and inhibit peptide elongation; bacteriocidal vs strept and most staph
4, Linezolid - blocks initiation step; bacteriocidal vs strept
Identify the major classes of antifolates that inhibit DNA biosynthesis (2).
- Sulfonamides - competitive antagonists of dihydropteroate synthase
- Trimethoprim - competitive antagonist of dihydrofolate reductase
Identify the major classes of DNA gyrase and Topo IV inhibitors (5)
Fluoroquinolones - inhibit topoisomerase II in Gram-negative bacteria and topoisomerase IV in Gram-positive bacteria.
Describe the spectra of antibacterial activity, clinical uses and common adverse reactions of: Aminoglycosides.
Spectra of activity - only bactericidal protein synthesis inhibitor;
Clinical uses - streptomycin = 2nd line Rx for TB + used in combination; Tobramycin and Gentamicin = used against Gram negative + combo with B-lactams;
Adverse effects - Ototoxic, Nephrotoxic
These aminoglycosides works great against Gram-negative bacteria and is used in combination with beta-lactams for synergistic effects.
Tobramycin and Gentamicin
This aminoglycoside is not as potent as Gentamicin but is resistant to enzymes that block it.
Amikacin - used if Gentamicin and Tobramycin fails
These drugs are used topically (have no effect systemically) and found in eyedrops.
Neomycin and Kanamycin
Describe the toxic effects of aminoglycosides.
Nephrotoxic - reversible damage of kidneys upon discontinuation of therapy
Ototoxicity - irreversible auditory/ vestibular damage; tinnitus
toxicity that can occur at >5 days
Describe the spectra of antibacterial activity, clinical uses and common adverse reactions of: Tetracyclines.
Spectra - bacteriostatic + BROAD spectrum (aerobic, anaerobic, Gram +/-), blocks elongation @ 30S;
Clinical uses - Rickettsial infections, typhus, Q fever, Chlamydia, respiratory tract infections, community-acquired staph, acne, Lyme disease
Adverse reactions - GI disturbances, binds calcium to stain teeth in children, photosensitization, liver disturbances
This type of tetracycline is taken oral/IV with LONG half-life to treat anthrax, malaria and Lyme Disease
Doxycycline
These drugs are reserved to treat multidrug resistant bacteria such as MRSA, VRE and penicillin-resistant strept
Tigecycline and Eravacycline
List at least 3 adverse effects of using Tetracyclines.
- Binds calcium to deform developing teeth and bony structures
- Photosensitization
- Hepatotoxic effects
Describe the spectra of antibacterial activity, clinical uses and common adverse reactions of: Macrolides.
Spectra - bacteriostatic, great for aerobic Gram-positive;
Clinical Uses - respiratory infections, community-acquired ammonia, bronchitis
Adverse effects - GI effects and Liver toxicity (better than tetracyclines)
This 50S inhibitor bacteriostatic drug is a new antibiotic used to treat MRSA, VRE and penicillin-resistant streptococci.
Linezolid
How do antifolate drugs differ from that of DNA Gyrase and Topo IV inhibitors?
Antifolate drugs inhibit biosynthesis of purines (block enzyme that works with folate to make DNA); whereas DNA gyrase inhibitors block bacterial DNA replication.
Describe the spectra of antibacterial activity, clinical uses and common adverse reactions of: Sulfonamides.
Spectra - bacteriostatic against Gram-negative and some Gram-positives;
Clinical uses - treat UTIs, IBDs (ulcerative colitis and Chron’s)
Adverse reactions - strongly HYPER-allergenic, hives, dermatitis, poorly soluble (crystalluria = painful obstruction)
Describe the spectra of antibacterial activity, clinical uses and common adverse reactions of: Trimethroprim.
Spectra - bacteriostatic against Gram-negatives and some Gram-positives OR bactericidal when combined as TMP-SMX;
Clinical uses - UTIs (E. Coli), salmonella, pneumocystis jiroveci pneumonia;
Adverse effects - rash, fever, urticaria, photosensitivity, GI effects
A combination therapy of these drugs results in primary adverse reactions of megaloblastic anemia and leukopenia if used >5 days.
TMP-SMX
Inhibition of _____ interferes with separation of replicated chromosomal DNA into daughter cells. Whereas, inhibition of ________ prevents the relaxation of supercoils of DNA needed for DNA replication.
Topoisomerase IV;
DNA Gyrase
Describe the spectra of antibacterial activity, clinical uses and common adverse reactions of: Fluoroquinolones.
Spectra - bacteriocidal, blocks Gyrase in Gram-negative and blocks Topo IV in Gram-positive;
Clinical uses - UTIs, diarrhea, Shigella, Salmonella, Toxigenic E. coli; Ciprofloxacin used to treat anthrax (by Bacillus anthracis);
Adverse reactions - GI disturbances (nausea, vomiting + diarrhea), can damage growing cartilage and cause arthropathy.
This fluoroquinolone is used to treat anthrax caused by…
Ciprofloxacin is prophylactic drug used to treat anthrax caused by Bacillus anthracis.
Levofloxacin, Gemifloxacin and moxifloxacin are aka __________ fluoroquines. Describe what they treat.
Respiratory fluoroquinolones (FQs) used to treat upper and lower respiratory tract infections.
Respiratory FQs can be used to treat _______ which is an opportunistic bacteria known to infect the lungs of patients with Cystic Fibrosis.
Pseudomonas aeroginosa
What antimicrobial, when overused can lead to C. difficile colitis? Define the function.
Clindamycin = 50S ribosomal inhibitor; It’s used to treat infections by aerobic and anaerobic Gram-positive bacteria. These include Clostridium perfringens, inflammatory acne and
What drug is main choice to treat anthrax (by Bacillus anthracis)? How does it work?
Ciprofloxacin (a fluoroquinolone) inhibits DNA Gyrase and Topoisomerase IV.
Define the selective toxicity. Provide a few targets.
Describes the properties that certain cell types make that make them targets for antimicrobial therapy. Some targets include the cell wall, fungal membranes, bacterial ribosomes and DHF reductase.
