Chlamydia trachomatis bacteria, TEM. Coloured transmission electron micrograph (TEM) of Chlamydia trachomatis bacteria (red/black) inside a cell (brown). These spherical bacteria are human parasites and live only inside an inclusion (white) in cells. Chlamydia trachomatis causes various types of genital, eye and lymph node infections. It causes sexually transmitted diseases: non-specific urethritis (NSU) affecting the urogenital tract and lymphogranuloma venereum (enlarged lymph glands). It also causes trachoma eye disease, a leading cause of blindness. It is treated with antibiotic drugs. Magnification: x5000 when printed 10cm wide.