**3. Other chlamydial conjunctivitis**

Other chlamydia subgroups that should be considered as causative agents of conjunctivitis are *C. psittaci* and *C. pneumoniae*.

*C. psittaci* is the causative agent of psittacosis, which is seen in people who have bird contact in their professional or private life. This infection may produce a wide spectrum of clinical manifestations, ranging from asymptomatic infection to severe systemic disease with severe pneumonia. The Association of *C. psittacine* with ocular adnexal lymphoma in humans has been reported.

C. psittaci is a cause of follicular conjunctivitis and epithelial keratitis. In cases with long-lasting follicular conjunctivitis with a story of close bird contact *C. psittaci* should be kept in consideration. The isolation of inclusion bodies in epithelial cells and the microorganism in tissue cultures are necessary for the diagnosis.

One of the most important differences between *C. psittaci* and *C. trachomatis* is the time required for treatment. While long-term treatments are required in *C. psittaci* eye infection, a single 1 g azithromycin dose is considered sufficient in *C. trachomatis* conjunctivitis. In *C. psittaci* conjunctivitis, oral tetracycline 500 mg four times a day or oral doxycycline 100 mg two times a day for 6 weeks should be used for treatment.

*C. pneumoniae* is a rare cause of chronic follicular conjunctivitis. For cases with long-lasting, resistant conjunctivitis, respiratory contact with cats having *C. pneumoniae* infection should be kept in mind. Limited documentation exists relating to *C. pneumoniae* seropositivity in cases of chronic follicular conjunctivitis. For clinicians treating patients presenting with chronic conjunctivitis unresponsive to conventional measures, obtaining serologic studies for *C. pneumoniae* may identify this association. Oral tetracycline 3–4 times a day is used for treatment [48].
