Erythromycin and azithromycin, both macrolide antibiotics, treat various bacterial infections. Their specific applications depend on the infecting organism’s susceptibility and the patient’s clinical presentation.
Respiratory Tract Infections
- Erythromycin: Effectively treats mild to moderate community-acquired pneumonia (CAP), particularly those caused by Streptococcus pneumoniae, Haemophilus influenzae, and Mycoplasma pneumoniae. It’s also used for whooping cough (pertussis) and acute exacerbations of chronic bronchitis. Azithromycin: A common choice for CAP, especially in outpatient settings, due to its once-daily dosing. It’s also effective against Chlamydia pneumoniae and atypical pneumonias. Azithromycin’s use in acute bronchitis is also established, though often secondary to other treatment options.
Skin and Soft Tissue Infections
Both antibiotics are used for uncomplicated skin and soft tissue infections (SSTIs). However, increasing resistance necessitates susceptibility testing before prescribing.
Sexually Transmitted Infections (STIs)
- Erythromycin: Treats early syphilis in individuals allergic to penicillin. It’s not the first-line treatment but a suitable alternative. Azithromycin: A single dose effectively treats Chlamydia trachomatis infections. It’s also used in regimens for treating gonorrhea, usually in combination with other antibiotics.
Other Applications
Erythromycin: Used to eradicate Helicobacter pylori, though often in combination therapy. Azithromycin: Used to treat infections such as Campylobacter jejuni gastroenteritis and traveler’s diarrhea, depending on the pathogen identified and local antibiotic guidelines.
Important Considerations
Always refer to current guidelines and local susceptibility patterns to ensure appropriate antibiotic selection. Resistance is a growing concern, so empirical treatment should be guided by local data and diagnostic testing when feasible. Consider potential drug interactions and contraindications before prescribing.
Limitations
Neither antibiotic is effective against many Gram-negative bacteria. Moreover, their use should be carefully evaluated due to the potential for adverse effects, such as gastrointestinal upset and QT prolongation.
