Protein inhibitors

• What are protein synthesis inhibitors?

  They are substances that interfere with the process of protein synthesis in bacteria.
• What is the distinct action of beta-lactams compared to polymyxins?

  Beta-lactams inhibit cell wall synthesis, while polymyxins disrupt the bacterial cell membrane.
• How do antibiotics selectively target bacteria during protein synthesis?

  They interrupt processes and enzyme functions that differ between bacterial and eukaryotic protein synthesis.

  
• What is the mechanism of action of aminoglycosides?

  Aminoglycosides bind to the bacterial ribosome and distort it, preventing protein synthesis initiation.
• Name three examples of aminoglycosides.

  Gentamicin, amikacin, and tobramycin.
• Why is serum concentration monitored for aminoglycosides?

  To prevent overdose toxicity, which could lead to hearing loss.
• What is streptomycin used for?

  It is an antibiotic used for the treatment of tuberculosis (TB).
• What is the spectrum of activity for aminoglycosides?

  Aminoglycosides are active against Gram-negative bacteria and staphylococci but inactive against streptococci and anaerobes.

  
• What are the clinical applications of aminoglycosides?

  They are used for life-threatening Gram-negative infections, severe skin infections, complicated urinary tract infections, and sepsis.
• Name some organisms that cause conditions treated by aminoglycosides.

  1. coli, Pseudomonas, Chlamydia, TB, Streptococcus B, and Listeria.
• How do macrolides function as protein synthesis inhibitors?

  Macrolides bind to the 50S ribosomal subunit and cause dissociation of peptidyl-tRNA.
• What types of bacteria are macrolides primarily used to treat?

  They are primarily used to treat Gram-positive bacteria.
• What are some examples of macrolides?

  Erythromycin, azithromycin, and clarithromycin.
• What is the mechanism of action of quinolones?

  Quinolones bind to unpaired DNA bases and interact with gyrase, which is essential for DNA replication.
• What are the generations of quinolones and their characteristics?

  1st generation: nalidixic acid; 2nd generation: ciprofloxacin; 3rd generation: lomefloxacin; 4th generation: trovafloxacin.
• What properties may each new generation of quinolone introduce?

  Wider spectrum of activity, better dosing, fewer drug interactions, and fewer side effects.
• What is the mechanism of action of metronidazole?

  Metronidazole damages bacterial DNA by producing toxic byproducts in anaerobic environments.

  
• Why does metronidazole not damage human DNA?

  Human DNA does not respire anaerobically and cannot metabolize metronidazole.

  
• How is metronidazole activated in the body?

  It is activated in the presence of pyruvate: ferredoxin oxidoreductase (POR), reducing it to a nitro radical anion.

  
• What is the role of tetrahydrofolic acid in bacteria and mammals?

  Tetrahydrofolic acid is essential for nucleotide synthesis in both bacteria and mammals, but synthesized differently.

  
• How does trimethoprim selectively inhibit bacterial tetrahydrofolic acid synthesis?

  Trimethoprim binds to bacterial dihydrofolate reductase (DHFR) 50 times more effectively than the mammalian form.

  
• What is the principle of the broth dilution test in antimicrobial susceptibility testing?

  The broth dilution test measures the minimum inhibitory concentration (MIC) by determining the lowest concentration that prevents bacterial growth.
• What is the disk diffusion method in antibiotic susceptibility testing?

  In disk diffusion, antibiotics diffuse into agar, creating a concentration gradient that inhibits the growth of sensitive organisms.

  
• What are antibiotic breakpoints?

  Antibiotic breakpoints are empirical predictions of resistance based on whether the zone of inhibition falls above or below a specified diameter.
• Why is a fully-quantitative MIC not possible with the disk-diffusion technique?

  Because antibiotic diffusion through agar is radial, not linear, making it difficult to quantify precisely.
• What are new and emerging methods for ascertaining resistance?

  They involve molecular and genetic methods to identify specific resistance genes, negating the need for phenotypic MIC testing.
• What is the significance of antimicrobial resistance in healthcare?

  Antimicrobial resistance impacts various branches of medicine, including surgery, cancer chemotherapy, and routine procedures.
• How does the presence of antimicrobial-tolerant strains lead to resistance?

  Sustained exposure to antibiotics allows tolerant strains to replicate, leading to increased resistance over time.
• What is the projected impact of antimicrobial resistance by 2050?

  Antimicrobial resistance deaths are projected to surpass current mortality rates if no action is taken.