Pharmacology Antibiotics Review: Tetracycline

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Questions and Answers

Which drug showed the highest effectiveness against methicillin resistant Staphylococcus aureus (MRSA) in the study?

  • Penicillin
  • Azithromycin
  • Trimethoprim (correct)
  • Ciprofloxacin

What percentage of fluoroquinolones were effective against methicillin susceptible Staphylococcus aureus (MSSA)?

  • 15%
  • 40%
  • 5%
  • 80% (correct)

Which drug showed resistance in 59.7% of Staphylococcus aureus isolates in the study?

  • Azithromycin (correct)
  • Vancomycin
  • Chloramphenicol
  • Penicillin

Based on the information provided, which drug is NOT mentioned as having resistance observed in the study?

<p>Vancomycin (C)</p> Signup and view all the answers

Among the listed drugs, which one is NOT recommended for treating MRSA based on the study results?

<p>Besifloxacin (C)</p> Signup and view all the answers

What is the main advantage of 4th generation fluoroquinolones over other fluoroquinolones?

<p>Greater efficacy against gram-positive bacteria (D)</p> Signup and view all the answers

Why do bacteria need two mutations to become resistant to 4th generation fluoroquinolones?

<p>To affect topoisomerase and efflux pumps (C)</p> Signup and view all the answers

What is the mechanism of action of Besifloxacin in treating bacterial conjunctivitis?

<p>Disrupting bacterial DNA replication (D)</p> Signup and view all the answers

How does the 4th generation of fluoroquinolones circumvent antibiotic resistance?

<p>By targeting a different enzyme than 2nd generation fluoroquinolones (C)</p> Signup and view all the answers

What is the significance of needing two mutations in bacteria to be destroyed by 4th generation fluoroquinolones?

<p>It emphasizes the dual target approach of these antibiotics (C)</p> Signup and view all the answers

Which class of antibiotics is known to inhibit bacterial DNA synthesis?

<p>Tetracyclines (C)</p> Signup and view all the answers

In the context of antibiotics, what is the main function of fluoroquinolones?

<p>Affect DNA synthesis (C)</p> Signup and view all the answers

Besifloxacin is commonly used to treat which eye condition?

<p>Bacterial conjunctivitis (B)</p> Signup and view all the answers

Which antibiotic class is most associated with resistance due to modification of the drug target?

<p>Aminoglycosides (A)</p> Signup and view all the answers

What is a common characteristic of bacterial strains that show resistance to antibiotics like besifloxacin?

<p>Reduced membrane permeability (B)</p> Signup and view all the answers

Which of the following fluoroquinolones showed the lowest MIC90s in the study?

<p>Besifloxacin (C)</p> Signup and view all the answers

In the study, which drug had a resistance greater than 70% for fluoroquinolones?

<p>Azithromycin (A)</p> Signup and view all the answers

Which drug had the highest resistance observed among the listed antibiotics in the ARMOR study?

<p>Oxacillin (C)</p> Signup and view all the answers

Compared to earlier-generation fluoroquinolones, which group had lower MIC90s overall?

<p>Besifloxacin, Gatifloxacin, Moxifloxacin (A)</p> Signup and view all the answers

Which antibiotic showed the highest resistance among presumed keratitis isolates during the period 2009-2019?

<p>Ciprofloxacin (D)</p> Signup and view all the answers

Which antibiotic class binds to the 50S ribosomal subunit and inhibits bacterial protein synthesis?

<p>Macrolides (D)</p> Signup and view all the answers

Which antibiotic is specifically mentioned for use in chlamydia and corneal ulcers?

<p>Ciprofloxacin (A)</p> Signup and view all the answers

Why is the use of a sulfa + anesthetic combination not recommended?

<p>The anesthetic contains PABA which can antagonize the sulfa component. (D)</p> Signup and view all the answers

Which generation of fluoroquinolones includes Levofloxacin and Moxifloxacin with superior effectiveness compared to Ciprofloxacin?

<p>3rd Generation (A)</p> Signup and view all the answers

Besifloxacin is formulated in which specific vehicle for ophthalmic use?

<p>DuraSite vehicle (D)</p> Signup and view all the answers

Which of the following is NOT a mechanism of antibiotic resistance mentioned in the text?

<p>Increased antibiotic permeability (D)</p> Signup and view all the answers

Which class of antibiotics is mentioned in the text as being effective for ocular conditions due to their ability to affect bacterial DNA synthesis?

<p>Fluoroquinolones (A)</p> Signup and view all the answers

Besifloxacin is specifically mentioned in the text as an antibiotic recommended for treating which ocular condition?

<p>Bacterial conjunctivitis (B)</p> Signup and view all the answers

What is highlighted in the text as the reason for the high and stable antibiotic resistance among ocular microbes?

<p>Inappropriate use of antibiotics (C)</p> Signup and view all the answers

What is one guideline highlighted for effective antimicrobial treatment of ocular conditions?

<p>Ensuring accurate diagnosis before treatment (D)</p> Signup and view all the answers

Why is Besifloxacin considered effective against bacteria?

<p>It has lower Minimum Inhibitory Concentration (MIC) for staphylococcal isolates. (A)</p> Signup and view all the answers

What is the significance of using a loading dose with great frequency in treating corneal ulcers?

<p>To bombard the infection with troops initially. (A)</p> Signup and view all the answers

How do practitioners justify the off-label use of 4th generation fluoroquinolones to treat corneal ulcers?

<p>By recognizing their effectiveness in treating corneal ulcers. (C)</p> Signup and view all the answers

What distinguishes Moxifloxacin from Gatifloxacin in terms of potency?

<p>Moxifloxacin has greater potency against Gram-positive bacteria. (C)</p> Signup and view all the answers

What is the role of Polymyxin B/Neomycin/Gramicidin Solutions in ocular treatment?

<p>To treat inflammation and bacteria simultaneously. (D)</p> Signup and view all the answers

What differentiates Tobradex ST from generic Tobradex?

<p>Tobradex ST has increased staying time on the ocular surface. (A)</p> Signup and view all the answers

Why is it important to be cautious when using Dexamethasone in patients with glaucoma?

<p>It has a higher correlation with increasing IOP in glaucoma patients. (D)</p> Signup and view all the answers

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