Extensive use of azithromycin has resulted in growing Streptococcus pneumoniae resistance.Aerobic and facultative Gram-positive microorganisms

Staphylococcus aureus (Methicillin-sensitive only)
Streptococcus agalactiae
Streptococcus pneumoniae
Streptococcus pyogenesAerobic and facultative anaerobic Gram-negative microorganisms

Haemophilus ducreyi
Haemophilus influenzae
Moraxella catarrhalis
Neisseria gonorrhoeae
Bordetella pertussis
Legionella pneumophilaAnaerobic microorganisms

Peptostreptococcus species
Prevotella biviaOther microorganisms

Chlamydophila pneumoniae
Chlamydia trachomatis
Mycoplasma genitalium
Mycoplasma pneumoniae
Ureaplasma urealyticum

Pregnancy and breastfeeding
No harm has been found with use during pregnancy. However, there are no adequate well-controlled studies in pregnant women.The safety of the medication during breastfeeding is unclear. It was reported that because only low levels are found in breast milk and the medication has also been used in young children, it is unlikely that breastfed infants would have adverse effects. Nevertheless, it is recommended that the drug be used with caution during breastfeeding. Airway diseases
Azithromycin appears to be effective in the treatment of chronic obstructive pulmonary disease through its suppression of inflammatory processes. And potentially useful in asthma and sinusitis via this mechanism. Azithromycin is believed to produce its effects through suppressing certain immune responses that may contribute to inflammation of the airways. Adverse effects
Most common adverse effects are diarrhea (5%), nausea (3%), abdominal pain (3%), and vomiting. Fewer than 1% of people stop taking the drug due to side effects. Nervousness, skin reactions, and anaphylaxis have been reported. Clostridium difficile infection has been reported with use of azithromycin. Azithromycin does not affect the efficacy of birth control unlike some other antibiotics such as rifampin. Hearing loss has been reported.Occasionally, people have developed cholestatic hepatitis or delirium.
Accidental intravenous overdose in an infant caused severe heart block, resulting in residual encephalopathy.In 2013 the FDA issued a warning that azithromycin "can cause abnormal changes in the electrical activity of the heart that may lead to a potentially fatal irregular heart rhythm." The FDA noted in the warning a 2012 study that found the drug may increase the risk of death, especially in those with heart problems, compared with those on other antibiotics such as amoxicillin or no antibiotic. The warning indicated people with preexisting conditions are at particular risk, such as those with QT interval prolongation, low blood levels of potassium or magnesium, a slower than normal heart rate, or those who use certain drugs to treat abnormal heart rhythms.It has been reported that azithromycin blocks autophagy and may predispose cystic fibrosis patients to mycobacterial infection. Pharmacology
Mechanism of action
Azithromycin prevents bacteria from growing by interfering with their protein synthesis. It binds to the 50S subunit of the bacterial ribosome, thus inhibiting translation of mRNA. Nucleic acid synthesis is not affected. Pharmacokinetics
Azithromycin is an acid-stable antibiotic, so it can be taken orally with no need of protection from gastric acids. It is readily absorbed, but absorption is greater on an empty stomach. Time to peak concentration (Tmax) in adults is 2.1 to 3.2 hours for oral dosage forms. Due to its high concentration in phagocytes, azithromycin is actively transported to the site of infection. During active phagocytosis, large concentrations are released.