Chlamydia trachomatis (CT) is an obligate intracellular pathogen that causes trachoma (a disease of the eye), conjunctivitis and pneumonia in neonates, nasopharyngeal infection, lower and upper genital tract infection in females, urogenital tract infection in males, and lymphogranuloma venereum. Culture isolation is no longer performed in most laboratories due to the exacting transport conditions, the need for highly trained staff to perform the testing and microscopy, and due to the expanded use of more sensitive nucleic acid amplification tests. CT is routinely propagated by inoculating the specimen onto mammalian cell monolayers followed by centrifugation and incubation. The infectious chlamydial elementary body attaches to the host cell, is internalized, and ultimately causes the formation of an intracellular inclusion after 48-72 hours of incubation at 370C. Intracellular inclusions are visualized by staining the cell monolayer with a fluorescently labeled monoclonal antibody directed against the chlamydial major outer membrane protein (MOMP). Cell monolayers are examined using an epi-fluorescent microscope for the presence of fluorescently labeled intracellular inclusions. This assay is currently available only as a research tool and is not available for routine clinical diagnosis. Contact the laboratory for additional information.