Moderate
Azithromycin × Ciprofloxacin
Macrolides×Fluoroquinolone antibacterials
Mechanism
Dual antibiotic therapy with additive QT prolongation. Used in severe infections (e.g., empirical therapy for community-acquired pneumonia in older patients at risk of atypical flora).
Symptoms
QT prolongation on ECG. Dizziness, syncope, palpitations. Rarely: polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, and ischaemic heart disease.
Management
The combination is appropriate in inpatient settings for indications (severe pneumonia, abdominal sepsis). ECG before start and at day 2 of therapy. Maintain potassium and magnesium. Avoid dual therapy in outpatient infections.