Azithromycin is a macrolide antibiotic with broad-spectrum bacteriostatic activity against many Gram-positive and Gram-negative bacteria. It also has activity against Mycoplasma pneumoniae, Treponema pallidum, Chlamydia sp. and Mycobacterium avium complex. In addition azithromycin has immunomodulating effects and is used in chronic respiratory inflammatory diseases, including cystic fibrosis, as an anti-inflammatory.