Approach
Empiric antibiotic therapy is the mainstay of treatment. Standard infection control procedures, including droplet transmission precautions, are sufficient as human-to-human transmission is rare.
Antibiotic treatment in adults
Tetracycline antibiotics are the treatment of choice.[12] Macrolides (e.g., erythromycin, azithromycin) and fluoroquinolones (e.g., moxifloxacin) are alternative second-line options when tetracyclines are contraindicated. Erythromycin is the best alternative, although it may be less efficacious than tetracyclines in severe illness, and treatment courses of up to 6 weeks may be required. Azithromycin may also be used, although there are reports of resistance.[28] Third-line treatment options include chloramphenicol and rifampin; however, there are many drug-drug interactions that limit the use of rifampin.
Macrolides are the preferred option in pregnant women, with chloramphenicol as a suitable second-line option. There is a lack of data to support the safety of chloramphenicol in pregnant women, and it should only be used if the benefits to the mother outweigh the risks to the fetus. It should not be used near term or during labor due to the risk of gray syndrome and bone marrow suppression in the neonate. Extreme caution should be used in pregnant women and is also recommended in breast-feeding women. Tetracycline is not recommended due to detrimental effects on the skeletal development of the fetus but can be given in extreme cases as a life saving measure if erythromycin is ineffective.[34][35] The use of doxycycline has been described in a case report.[36]
Oral therapy is indicated in mild-to-moderate disease. Intravenous therapy is required in patients who are severely ill (i.e., with signs of pulmonary disease with diffuse involvement and fever, sepsis, disseminated intravascular coagulation, or findings consistent with other organ involvement such as the spleen or liver). A response is usually seen within 24 to 48 hours. The treatment course is variable; however, 2 to 3 weeks is usually sufficient to prevent relapse. Longer courses of up to 6 weeks may be required in some patients, particularly those with severe illness.
Chlamydia psittaciis susceptible to tetracyclines, macrolides, chloramphenicol, fluoroquinolones, and rifampin. However, in one study, the minimal inhibitory concentration of fluoroquinolones was 0.25 micrograms/L compared with 0.05 to 0.20 micrograms/L for doxycycline, suggesting that there is the possibility of treatment failure with fluoroquinolones.[37]
Topical erythromycin is recommended for C psittaci conjunctivitis.[3]
Antibiotic treatment in children
Erythromycin is the treatment of choice in children. Azithromycin may be used as an alternative. Chloramphenicol is a suitable second-line option; however, extreme caution should be used in children. Gray syndrome (also known as gray baby syndrome), a type of circulatory collapse that is potentially life-threatening, has been reported in premature and newborn infants receiving chloramphenicol, and more rarely in children ages up to 2 years. As with adults, intravenous antibiotic therapy is indicated in patients who are severely ill.
It is generally recommended that tetracyclines are not used in children <8 years of age due to the risk of tooth discoloration; however, they may be used in younger children if the benefits outweigh the risks, especially in life-threatening situations where other therapies are not effective.[12]
Topical erythromycin is recommended for C psittaci conjunctivitis.[3]
Supportive therapy
Patients with severe pneumonitis require oxygen therapy. Complications such as endocarditis, hepatitis, myocarditis, arthritis, and encephalitis may occasionally occur and require appropriate treatment.
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