Chlamydia infection. Immunofluorescent light micrograph of chlamydia bacteria (Chlamydia sp., yellow) infecting cells. These bacteria cause eye, genital and systemic diseases in humans. Genital chlamydial infections include urethritis in men, cervicitis in women and lymphogranuloma venereum, a venereal disease more common in tropical areas. Treatment is with suitable antibiotics. Giemsa stain. Immunofluorescence is a staining technique that uses antibodies to attach fluorescent dyes to cells and tissues. Magnification unknown.