In the United States, C trachomatis is the most common bacterial cause of STIs, including Nongonococcal urethritis and epididymitis in men Cervicitis, urethritis, and pelvic inflammatory disease in women Proctitis, lymphogranuloma venereum, and reactive arthritis (Reiter syndrome) in all patients Maternal transmission of C trachomatis causes neonatal conjunctivitis and neonatal pneumonia.