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Questions and Answers
What does selective toxicity ensure in antimicrobial drugs?
What does selective toxicity ensure in antimicrobial drugs?
What is the therapeutic dose of an antimicrobial drug?
What is the therapeutic dose of an antimicrobial drug?
How is the therapeutic index (TI) calculated?
How is the therapeutic index (TI) calculated?
What does a lower therapeutic index indicate?
What does a lower therapeutic index indicate?
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What is the significance of TD50 in the context of antimicrobial drugs?
What is the significance of TD50 in the context of antimicrobial drugs?
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What discovery is credited to Alexander Fleming in 1928?
What discovery is credited to Alexander Fleming in 1928?
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Which term describes antibiotics that inhibit bacterial growth rather than killing them?
Which term describes antibiotics that inhibit bacterial growth rather than killing them?
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What is the role of antivirals in treating infections?
What is the role of antivirals in treating infections?
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What are antiprotozoal drugs specifically designed to target?
What are antiprotozoal drugs specifically designed to target?
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Which type of antibiotic is preferred in severe infections for rapid bacterial eradication?
Which type of antibiotic is preferred in severe infections for rapid bacterial eradication?
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Which mechanism is NOT typically associated with bactericidal agents?
Which mechanism is NOT typically associated with bactericidal agents?
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Which of the following antibiotics was developed through the purification and development work of Howard Florey and Ernst Chain?
Which of the following antibiotics was developed through the purification and development work of Howard Florey and Ernst Chain?
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Which category of antimicrobial agents specifically targets fungi?
Which category of antimicrobial agents specifically targets fungi?
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What does the '50S' in 50S ribosomes indicate?
What does the '50S' in 50S ribosomes indicate?
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Which rRNA is contained in the 30S ribosomal subunit?
Which rRNA is contained in the 30S ribosomal subunit?
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Which antibiotic is known to block aminoacyl tRNA binding to the A site?
Which antibiotic is known to block aminoacyl tRNA binding to the A site?
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What is a primary mechanism through which aminoglycosides promote protein mistranslation?
What is a primary mechanism through which aminoglycosides promote protein mistranslation?
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Which of the following is a characteristic of aminoglycosides?
Which of the following is a characteristic of aminoglycosides?
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Which mechanism is NOT a way bacteria can develop resistance to aminoglycosides?
Which mechanism is NOT a way bacteria can develop resistance to aminoglycosides?
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What action do macrolides and clindamycin have on the ribosome?
What action do macrolides and clindamycin have on the ribosome?
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Which of the following correctly matches the ribosomal subunit with its respective rRNA components?
Which of the following correctly matches the ribosomal subunit with its respective rRNA components?
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What is the primary target of cycloserine in the treatment of tuberculosis?
What is the primary target of cycloserine in the treatment of tuberculosis?
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Which class of antibiotics is known to inhibit the binding process in protein synthesis?
Which class of antibiotics is known to inhibit the binding process in protein synthesis?
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Which mechanism of action is associated with sulfonamides?
Which mechanism of action is associated with sulfonamides?
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What is the composition of bacterial ribosomes?
What is the composition of bacterial ribosomes?
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Which antibiotic class disrupts peptidoglycan cross-linking in bacterial cell walls?
Which antibiotic class disrupts peptidoglycan cross-linking in bacterial cell walls?
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What type of antibiotics bind to membrane phospholipids causing leakage?
What type of antibiotics bind to membrane phospholipids causing leakage?
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Antibiotics that interfere with DNA or RNA synthesis are represented by which class?
Antibiotics that interfere with DNA or RNA synthesis are represented by which class?
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Which is NOT a mechanism of action for antimicrobial agents?
Which is NOT a mechanism of action for antimicrobial agents?
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What mechanism allows bacteria to resist chloramphenicol?
What mechanism allows bacteria to resist chloramphenicol?
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Which condition is associated with chloramphenicol toxicity in neonates?
Which condition is associated with chloramphenicol toxicity in neonates?
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Which type of bacteria are macrolides primarily effective against?
Which type of bacteria are macrolides primarily effective against?
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What phenomenon describes the ability of bacteria to resist multiple drugs within the same group?
What phenomenon describes the ability of bacteria to resist multiple drugs within the same group?
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Which bacterial group is NOT effectively targeted by macrolides?
Which bacterial group is NOT effectively targeted by macrolides?
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What is a common side effect of chloramphenicol regarding bone marrow function?
What is a common side effect of chloramphenicol regarding bone marrow function?
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Which mechanism contributes to bacterial resistance against macrolides?
Which mechanism contributes to bacterial resistance against macrolides?
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What is the primary classification of chloramphenicol?
What is the primary classification of chloramphenicol?
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Study Notes
Antimicrobial Agents
- Alexander Fleming discovered the antibacterial properties of Penicillium mold in 1928.
- Howard Florey and Ernst Chain purified and developed penicillin in the 1940s, leading to its widespread use as an antibiotic.
Antimicrobial Definitions
- Antibiotics target bacteria, either killing them (bactericidal) or inhibiting their growth (bacteriostatic).
- Antivirals target viruses, inhibiting their development and replication.
- Antiprotozoal drugs target protozoa, single-celled organisms that cause diseases such as malaria and amoebiasis.
- Antifungals target fungi, either killing them (fungicides) or inhibiting their growth (fungistatics).
Antimicrobial Mechanisms of Action
- Bactericidal agents kill bacteria by disrupting cell wall synthesis, damaging cell membranes, or interfering with vital cellular functions.
- Bacteriostatic agents inhibit bacterial growth, preventing them from multiplying.
General Characteristics of Antimicrobial Drugs
- Selective toxicity: Antimicrobial drugs should target microbial pathogens while minimizing harm to the host.
- Therapeutic dose: The drug level required for clinical treatment of a particular infection.
- Toxic dose: The drug level at which the agent becomes too toxic for the host.
- Therapeutic index: The ratio of the toxic dose to the therapeutic dose.
Antimicrobial Spectrum of Activity
- Narrow-spectrum antibiotics target a limited range of bacterial species.
- Broad-spectrum antibiotics target a wider range of bacterial species.
Protein Synthesis Inhibitors
- Aminoglycosides bind to the 30S subunit of the bacterial ribosome, causing mismatching between mRNA codons and charged tRNA, leading to protein mistranslation.
- Chloramphenicol inhibits protein synthesis by binding to the 50S subunit of the bacterial ribosome, blocking peptide bond formation.
- Macrolides bind to the 50S ribosomal subunit, blocking the translocation step of protein synthesis.
- Ketolides are a structurally related class of antibiotics to macrolides.
Aminoglycosides
- Mechanism of action: Bind to the 30S ribosomal subunit, leading to protein mistranslation.
- Mechanism of resistance: Decreased accumulation within the bacterium, drug inactivation, and mutations in the ribosome binding site.
- Spectrum of activity: Broad spectrum, effective against many Gram-positive and Gram-negative bacteria.
Chloramphenicol
- Mechanism of action: Binds to the 50S ribosomal subunit, blocking peptidyl transferase.
- Bacterial resistance: Inactivation of chloramphenicol by bacterial enzymes, and efflux pumps.
- Side effects: Reversible dose-dependent bone marrow suppression, gray baby syndrome, and neurologic abnormalities.
Macrolides and Ketolides
- Mechanism of action: Bind to the 50S ribosomal subunit, blocking the translocation step of protein synthesis.
- Bacterial resistance: Inhibition of drug entry, enzyme-mediated ribosome binding site alteration, and mutations in the ribosome binding site.
- Spectrum of activity: Narrow spectrum, effective against specific types of infections, such as respiratory infections.
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Description
Explore the history and definitions of various antimicrobial agents, including antibiotics, antivirals, antifungals, and antiprotozoals. This quiz covers key figures like Alexander Fleming and pivotal discoveries in medicine. Test your knowledge on mechanisms of action for these compounds.
