Introduction: Quinolones and fluoroquinolones are powerful broad‑spectrum antibacterial agents that act by inhibiting bacterial DNA gyrase and topoisomerase IV, disrupting DNA replication and causing bactericidal double‑strand breaks. Fluoroquinolones (e.g., ciprofloxacin, levofloxacin, moxifloxacin) have enhanced potency, better tissue penetration and expanded activity against Gram‑negative, some Gram‑positive and atypical pathogens. Understanding mechanism of action, spectrum of activity, pharmacokinetics/pharmacodynamics (AUC/MIC), resistance mechanisms (gyrA/parC mutations, qnr, efflux), and key adverse effects (tendinopathy, QT prolongation, CNS effects) is essential for B.Pharm students. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which bacterial enzymes are the primary targets of quinolones and fluoroquinolones?
- Peptidyl transferase and ribosomal subunits
- DNA gyrase (topoisomerase II) and topoisomerase IV
- RNA polymerase and DNA polymerase III
- Transpeptidase and carboxypeptidase
Correct Answer: DNA gyrase (topoisomerase II) and topoisomerase IV
Q2. Addition of a fluorine atom at C‑6 in fluoroquinolones primarily results in which effect?
- Decreased oral absorption and increased renal clearance
- Enhanced antibacterial potency and broader spectrum with improved tissue penetration
- Selective activity only against anaerobes
- Conversion to bacteriostatic agents
Correct Answer: Enhanced antibacterial potency and broader spectrum with improved tissue penetration
Q3. The bactericidal activity of fluoroquinolones is best described as:
- Time‑dependent killing with minimal post‑antibiotic effect
- Concentration‑dependent killing with significant post‑antibiotic effect
- Only bacteriostatic at therapeutic concentrations
- Dependent on presence of beta‑lactamase enzymes
Correct Answer: Concentration‑dependent killing with significant post‑antibiotic effect
Q4. Which fluoroquinolone is classified as a “respiratory” agent with enhanced Gram‑positive and atypical coverage?
- Ciprofloxacin
- Norfloxacin
- Moxifloxacin
- Enoxacin
Correct Answer: Moxifloxacin
Q5. Which fluoroquinolone has the strongest clinically useful activity against Pseudomonas aeruginosa?
- Moxifloxacin
- Levofloxacin
- Ciprofloxacin
- Nalidixic acid
Correct Answer: Ciprofloxacin
Q6. The most common chromosomal mechanism of high‑level fluoroquinolone resistance is:
- Increased outer membrane porin expression
- Point mutations in gyrA and parC genes encoding target enzymes
- Enhanced beta‑lactamase production
- Inactivation by cytosolic acetyltransferases only
Correct Answer: Point mutations in gyrA and parC genes encoding target enzymes
Q7. Which plasmid‑mediated determinant confers reduced susceptibility to fluoroquinolones by protecting DNA gyrase?
- mecA
- qnr genes
- blaTEM
- vanA
Correct Answer: qnr genes
Q8. Concomitant administration of which agents markedly reduces oral absorption of many fluoroquinolones?
- Proton pump inhibitors (no effect)
- Divalent and trivalent cation‑containing products such as antacids, calcium and iron supplements
- Loop diuretics
- Topical corticosteroids
Correct Answer: Divalent and trivalent cation‑containing products such as antacids, calcium and iron supplements
Q9. Which adverse effect is classically associated with fluoroquinolones and may lead to tendon rupture?
- Hepatic steatosis
- Tendinopathy and tendon rupture
- Pancreatitis
- Hyperglycemia only
Correct Answer: Tendinopathy and tendon rupture
Q10. Fluoroquinolones are generally contraindicated in pregnancy and growing children because of which risk?
- Ototoxicity leading to deafness
- Cartilage toxicity and arthropathy in developing joints
- Severe hypoglycemia
- Complete hair loss
Correct Answer: Cartilage toxicity and arthropathy in developing joints
Q11. Which PK/PD parameter best correlates with clinical efficacy of fluoroquinolones?
- Time above MIC (T>MIC)
- Peak/MIC ratio only
- AUC/MIC (area under the concentration‑time curve divided by MIC)
- Protein binding percentage
Correct Answer: AUC/MIC (area under the concentration‑time curve divided by MIC)
Q12. Which fluoroquinolone has relatively better anaerobic activity and is often used in intra‑abdominal infections?
- Ciprofloxacin
- Levofloxacin
- Moxifloxacin
- Nalidixic acid
Correct Answer: Moxifloxacin
Q13. Prolongation of the QT interval is a notable risk with which fluoroquinolone?
- Levofloxacin (lowest risk of QT prolongation among options)
- Moxifloxacin
- Ciprofloxacin (no QT effect)
- Norfloxacin (protects QT interval)
Correct Answer: Moxifloxacin
Q14. The bactericidal action of fluoroquinolones involves stabilization of a cleavage complex that results in:
- Inhibition of peptidoglycan cross‑linking
- Accumulation of double‑stranded DNA breaks and cessation of replication
- Blockade of folate synthesis
- Inhibition of protein translocation across the membrane
Correct Answer: Accumulation of double‑stranded DNA breaks and cessation of replication
Q15. Which clinical pathogens are considered “atypical” but are well covered by respiratory fluoroquinolones?
- Enterococcus faecalis and Bacteroides fragilis
- Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila
- Pseudomonas aeruginosa and Acinetobacter baumannii
- Staphylococcus epidermidis and Corynebacterium species
Correct Answer: Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila
Q16. Fluoroquinolones have reliable activity against methicillin‑resistant Staphylococcus aureus (MRSA):
- True for all fluoroquinolones
- False; activity against MRSA is variable and generally unreliable
- True only for ciprofloxacin
- True only in combination with beta‑lactams
Correct Answer: False; activity against MRSA is variable and generally unreliable
Q17. Which class effect contributes to rapid selection of resistant mutants when fluoroquinolones are used as monotherapy for high‑burden infections?
- Time‑dependent killing eliminates resistant subpopulations
- Concentration‑dependent killing with inadequate AUC/MIC selects resistant mutants if exposure is suboptimal
- Complete sterilization of all bacteria regardless of dose
- Immediate induction of beta‑lactamases
Correct Answer: Concentration‑dependent killing with inadequate AUC/MIC selects resistant mutants if exposure is suboptimal
Q18. Which fluoroquinolone generally does NOT require renal dose adjustment because it is primarily eliminated non‑renally?
- Ciprofloxacin
- Levofloxacin
- Moxifloxacin
- Norfloxacin
Correct Answer: Moxifloxacin
Q19. Which adverse effect prompted a boxed warning from regulatory agencies due to rapid onset and potential permanence?
- Peripheral neuropathy and central nervous system effects
- Transient mild rash only
- Benign reversible hair thinning
- Minor oral mucositis
Correct Answer: Peripheral neuropathy and central nervous system effects
Q20. Fluoroquinolones are important second‑line drugs in the management of which disease due to activity against Mycobacterium tuberculosis?
- Uncomplicated urinary tract infection only
- Multidrug‑resistant tuberculosis (MDR‑TB)
- Viral pneumonia
- Fungal meningitis
Correct Answer: Multidrug‑resistant tuberculosis (MDR‑TB)
Q21. Which mechanism is commonly encoded on plasmids and contributes to low‑level fluoroquinolone resistance that facilitates selection of higher resistance?
- qnr proteins that protect target enzymes
- Chromosomal loss of porins only
- Large genomic deletions of gyrA
- Overproduction of peptidoglycan
Correct Answer: qnr proteins that protect target enzymes
Q22. Ciprofloxacin is known to interact with which hepatic enzyme, potentially increasing levels of coadministered substrates?
- CYP3A4 induction
- CYP1A2 inhibition
- UDP‑glucuronosyltransferase activation
- P‑glycoprotein synthesis upregulation
Correct Answer: CYP1A2 inhibition
Q23. Which laboratory method is the gold standard for determining fluoroquinolone susceptibility (quantitative MIC)?
- Disk diffusion without standards
- Broth microdilution to determine MIC
- Gram stain morphology assessment
- Serologic antibody titer
Correct Answer: Broth microdilution to determine MIC
Q24. Which statement about fluoroquinolone spectrum is correct?
- All fluoroquinolones uniformly cover anaerobes and enterococci
- Activity varies: good Gram‑negative coverage, variable Gram‑positive, good atypical coverage, and variable anaerobic activity
- They are active only against Gram‑positive cocci
- They have no activity against intracellular organisms
Correct Answer: Activity varies: good Gram‑negative coverage, variable Gram‑positive, good atypical coverage, and variable anaerobic activity
Q25. Which of the following is NOT a fluoroquinolone?
- Ciprofloxacin
- Levofloxacin
- Nalidixic acid
- Moxifloxacin
Correct Answer: Nalidixic acid
Q26. Concurrent systemic corticosteroid therapy increases the risk of which serious fluoroquinolone adverse event?
- Hepatic failure
- Tendon rupture
- Neutropenia
- Hyperkalemia
Correct Answer: Tendon rupture
Q27. Which fluoroquinolone is most commonly implicated in photosensitivity reactions?
- Lomefloxacin and some older agents (higher phototoxic potential)
- All fluoroquinolones have no phototoxicity risk
- Moxifloxacin exclusively prevents photosensitivity
- Nalidixic acid eliminates sunlight sensitivity
Correct Answer: Lomefloxacin and some older agents (higher phototoxic potential)
Q28. For optimal prevention of resistance and clinical success with Gram‑negative infections, fluoroquinolone dosing strategies aim to maximize which metric?
- Time above MIC (T>MIC) as the only goal
- AUC/MIC ratio to reach target exposure
- Minimal inhibitory concentration regardless of exposure
- Protein binding alterations
Correct Answer: AUC/MIC ratio to reach target exposure
Q29. A double mutation in gyrA combined with a mutation in parC typically results in:
- Increased susceptibility to fluoroquinolones
- High‑level fluoroquinolone resistance
- Resistance only to beta‑lactams
- Complete loss of bacterial virulence without resistance
Correct Answer: High‑level fluoroquinolone resistance
Q30. Which clinical precaution is important when prescribing fluoroquinolones to elderly patients?
- No precautions; they are safer in elderly than young adults
- Monitor for tendinopathy, falls, QT prolongation and CNS effects, especially with concomitant corticosteroids or QT‑prolonging drugs
- Only risk is increased appetite
- Only gastrointestinal side effects require monitoring
Correct Answer: Monitor for tendinopathy, falls, QT prolongation and CNS effects, especially with concomitant corticosteroids or QT‑prolonging drugs
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
Mail- Sachin@pharmacyfreak.com