Direct fluorescent monoclonal antibody stain for rapid detection of infant Chlamydia trachomatis infections.

A method of direct fluorescent antibody staining for rapid diagnosis of Chlamydia trachomatis infections in infants is described. This method utilized a fluorescein-conjugated species-specific monoclonal antibody to C trachomatis for detecting chlamydial elementary bodies in smears of the conjunctiva, nasopharynx, oropharynx, anus, and vagina. The sensitivity of direct fluorescent antibody staining was compared with isolation of the organisms in McCoy cells. Thirty-nine infants with purulent conjunctivitis were studied. Diagnosis of C trachomatis conjunctivitis was correctly made by smear in all 16 infants when inflamed eyes were sampled. Positive smears were obtained from 12/14 culture-positive and 4/16 culture-negative nasopharyngeal specimens from infants with chlamydial conjunctivitis. All nasopharyngeal cultures and smears from infants with nonchlamydial conjunctivitis were negative. These results indicate that the direct smear test is a sensitive and specific test for diagnosing C trachomatis infection of the eye and nasopharynx in infants, and this test can be completed within one hour of specimen collection.