1. Antibacterial Applications
Gram-positive bacteria: Effective against Streptococcus pyogenes (strep throat), Streptococcus pneumoniae (pneumonia), Staphylococcus aureus (skin infections), and Corynebacterium diphtheriae.
Gram-negative bacteria: Covers Bordetella pertussis (whooping cough), Legionella pneumophila (Legionnaires' disease), Neisseria gonorrhoeae (gonorrhea), and Haemophilus influenzae.
Atypical pathogens: Targets Mycoplasma pneumoniae (walking pneumonia), Chlamydia trachomatis (chlamydia), and Treponema pallidum (syphilis in penicillin-allergic patients).
2. Clinical Uses
Respiratory infections: Community-acquired pneumonia, bronchitis, and pertussis.
Skin/soft tissue infections: Acne vulgaris (topical erythromycin), cellulitis, and erysipelas.
Sexually transmitted infections (STIs): Chlamydia and syphilis (alternative to penicillin).
Ophthalmic infections: Conjunctivitis and neonatal ocular prophylaxis.
Gastrointestinal motility: Low-dose erythromycin acts as a motilin receptor agonist to treat gastroparesis.
3. Unique Advantages
Penicillin allergy alternative: Safe for patients allergic to β-lactam antibiotics.
Anti-inflammatory effects: Used in chronic inflammatory conditions like diffuse panbronchiolitis (DPB).
Topical formulations: Minimize systemic side effects in acne treatment.
4. Veterinary Use
Treats infections in livestock, poultry, and pets (e.g., mastitis in cows, respiratory infections in pigs).
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