Term
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Definition
Inhibition of cell wall synthesis
2. Disruption of cell membrane structure or function
3. Inhibition of protein synthesis
4. Inhibition of nucleic acid synthesis, structure or function
5. Block metabolic reactions |
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Term
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Definition
Drug kills pathogens without
damaging the host. |
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Term
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Definition
Kill bacterial directly
Chloramphenicol
Erythromycin
Clindamycin
Sulfonamides
Trimethoprim
Tetracyclines |
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Term
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Definition
Prevent bacterial from growing
Aminoglycosides
Beta-lactams
Vancomycin
Quinolones
Rifampin
Metronidazole |
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Term
| Mechanisms of antibiotic resistance |
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Definition
1. Enzymatic destruction of drug
2. Prevention of penetration of
drug
3. Alteration of drug's target site
4. Rapid ejection of the drug |
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Term
| T/F: Antibiotics that inhibit bacterial protein synthesis target the 80S ribosomes and therefore do not affect eukaryotes which have 70S ribosomes. |
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Definition
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Term
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Definition
• Bind to 30S subunit and interferes with the attachment of the tRNA
carrying amino acids to the ribosome
• The term "tetracycline" is also used to denote the four-ring system of this
compound;
Block attachment of tRNA
(Tetracycline, Doxycycline, Minocycline)
• Broad spectrum and low cost
• Bacteriostatic |
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Term
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Definition
Inhibitors of 30S ribosome subunit
Bind to bacterial ribosome on 30S subunit; and blocks formation of
initiation complex. Both actions lead to mis-incorporation of amino acids
– Causes Misreading of mRNA
(Streptomycin, neomycin, gentamycin) |
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Term
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Definition
• Common subunit: Amino
sugars
• Highly polar molecules
• do not distribute well into
body compartments. |
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Term
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Definition
• Mode of action - Bind to bacterial ribosome on 30S subunit;
and blocks formation of initiation complex.
• Spectrum of Activity -Many gram-negative and some grampositive
bacteria.
• Type - Bactericidal antibiotics (rare among protein synthesis
inhibitor)
• Pharmacokinetics - Aminoglycosides are poorly lipid soluble
and, therefore, they cannot be given orally, but must be
administered by intramuscular injection.
• Adverse effect – Nephrotoxicity and toxic to the 8th cranial
nerve (ototoxic).
• Synergy - The aminoglycosides synergize with β-lactam
antibiotics. The β-lactams inhibit cell wall synthesis and thereby
increase the permeability of the aminoglycosides.
Narrow therapeutic range - severe side effects:
• Renal toxicity most important and most common
• Inhibition of phospholipases and other enzymes result in inhibition of
prostaglandin synthesis
• Ototoxicity
• Damage to hair cells, tinnitus, loss of hearing
• Vestibular damage, headache, nausea, dizzy
Resistance:
• Mutation of the ribosomal binding site
• Decreased uptake of the antibiotic (Anaerobic bacteria)
• Increased expulsion of the antibiotic from the cell
• Enzymatic modification which break down aminoglycosides |
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Term
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Definition
first antibiotic active against tuberculosis
• From the actinobacterium Streptomyces griseus.
• A bactericidal antibiotic.
• Adverse effects of this medicine are ototoxicity, nephrotoxicity, fetal auditory
toxicity, and neuromuscular paralysis. It is now rarely used in the developed
world. |
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Term
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Definition
the most commonly used covering Gram-negative aerobes.
• It is very effective when used correctly.
• Safe. If levels are monitored appropriately, severe renal impairment and ototoxicity rarely occur.
Heat stable (Even through autoclave)
Extended use is dangerous |
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Term
Which of the following statements about aminoglycosides is TRUE?
A) include streptomycin
B) bind to the 30S ribosomal subunit of the bacterial ribosome
C) cause misreading of the mRNA code
D) A and B
E) A, B and C |
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Definition
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Term
| Tetracycline: adverse effects |
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Definition
• staining and impairment of the structure of bone and teeth.
• Should be avoided in pregnancy, breast feeding and children under 12
years as they bind to calcium in growing bones and teeth causing
discoloration.
• Rarely used now due to serious side effects – aplastic anemia, irreversible
damage to bone marrow, leukemia and Gray baby syndrome |
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Term
Which of the following mechanisms can make a bacterium resistant to tetracycline?
A) chemical modification of the drug
B) pumping the drug out of the cell
C) enhancing the binding of the drug to the ribosome
D) A and B
E) A, B and C |
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Definition
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Term
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Definition
• Source: Isolated from Streptomyces venezuelae; longer derived from
natural source.
• well absorbed after oral administration
• Very broad spectrum (almost all bacteria except Pseudomonas
aeruginosa)
• Very toxic, restricted uses, can cause irreversible damage to bone marrow |
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Term
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Definition
The macrolides inhibit translocation by binding to 50S ribosomal subunit
the presence of a macrolide ring, a large macrocyclic lactone ring
Eg. (Erythromycin,Clarithromycin (Biaxin),Azithromycin (Zithromax; Zitromax),Roxithromycin (Rulid),Dirithromycin (Dynabac))
• made by Streptomyces
• Narrow spectrum (Gram +, Mycoplasma, T.
palidum)
• Bacteriostatic
• It may be given orally or parenterally
• Macrolides are widely distributed in thebody
• Generally safe drugs |
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Term
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Definition
• Also inhibits protein synthesis (attaches to bacterial ribosomes)
• Erythromycin has a narrow Gram (+) spectrum
• (side effects: fairly low toxicity!)
– Given to children
• Taken orally for Mycoplasma pneumonia, legionellosis, Chlamydia, pertussis,
diptheria
• and as a prophylactic prior to intestinal surgery
• Newer semi-synthetic macrolides – clarithomycin, azithromycin |
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Term
Erythromycin binds to the ______ subunit of bacterial ribosomes thereby inhibiting
peptide chain _______.
A) 50S; initiation
B) 50S; elongation
C) 30S; initiation
D) 30S; elongation
E) 30S; termination |
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Definition
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Term
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Definition
Oxazolidinones inhibits protein synthesis by preventing formation of the ribosome complex that initiated protein synthesis
Linezolid
• Narrow-spectrum (Gram-positives)
• Totally synthetic, hard to have resistant bacterial
• It is used for the treatment of serious infections caused by
Gram-positive bacteria that are resistant to several other
antibiotics
• Discovered in the 1990s and first approved for use in 2000
• Linezolid is very expensive, costing approximately US$100
per pill in the United States |
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Term
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Definition
(Zyvox)
• When used for short periods, linezolid is a relatively safe
drug.
• Bone marrow suppression, may occur during linezolid long-term treatment;
• when given by mouth: the entire dose reaches the bloodstream, as if it had been given intravenously. |
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