Fluoroquinolones

A 62-year-old man with chronic kidney disease (eGFR 25 mL/min) presents with acute exacerbation of chronic bronchitis due to Haemophilus influenzae. Which fluoroquinolone is best avoided in this patient, and what is the distinguishing toxicity concern?

A 52-year-old man with chronic kidney disease (eGFR 35 mL/min/1.73m²) presents with acute exacerbation of chronic bronchitis caused by *Haemophilus influenzae*. Which feature best distinguishes moxifloxacin from levofloxacin as the preferred agent in this clinical scenario?

A 42-year-old woman from Mumbai with a history of myasthenia gravis presents with acute exacerbation of symptoms: ptosis, diplopia, and generalized muscle weakness. She was empirically started on ciprofloxacin 500 mg twice daily 2 days ago for a suspected respiratory tract infection. Her symptoms have worsened significantly since starting the antibiotic. Neurological examination confirms worsening of ocular and bulbar signs. What is the mechanism by which this fluoroquinolone is likely exacerbating her myasthenia gravis?

A 58-year-old man from Delhi presents with acute exacerbation of chronic bronchitis with productive cough, fever (38.5°C), and dyspnea for 3 days. Chest X-ray shows left lower lobe infiltrate. Sputum culture is pending. He has a history of type 2 diabetes (HbA1c 8.2%) and takes metformin. On examination, he is alert, BP 128/82 mmHg, HR 92/min, RR 24/min. You decide to start empirical antibiotic therapy. Which fluoroquinolone would be most appropriate, and why?

A 42-year-old woman with uncomplicated urinary tract infection caused by Escherichia coli (susceptible to all fluoroquinolones) presents for outpatient management. Which fluoroquinolone is the drug of choice for empiric treatment of uncomplicated cystitis?