Bird Zithro (Azithromycin) is a bird antibiotic that is used for systemic and local infections in pigeons, pet birds, and exotic birds. This antibiotic is effective against gram-positive bacteria, as well as some gram-negative bacteria, spirochetes, anaerobic bacteria, and other types of microorganisms. Bird ZithroTM is also effective against Chlamydia psittaci in cockatiels.