A 28-year-old man comes to the office due to 4 days of urethral discharge and dysuria. The patient had similar symptoms a month ago, and urethral swab Gram stain at that time revealed numerous neutrophils but no organisms. He was treated with a single dose of azithromycin, and his symptoms resolved completely. The patient has no other medical conditions and takes no medications. He drinks alcohol socially and does not use tobacco or illicit drugs. The patient had multiple sexual partners in the past but has been in a monogamous relationship with a female partner for the past 3 months. His partner has no symptoms and takes oral contraceptives. The patient is afebrile. Physical examination shows mucoid discharge from the urethral meatus. Urine dipstick test is positive for leukocyte esterase. Nucleic acid amplification testing is positive for Chlamydia trachomatis. Which of the following is the most likely cause of symptom recurrence in this patient?
Chlamydia trachomatis is an obligate intracellular gram-negative bacterium transmitted through oral, anal, or vaginal intercourse. It is the leading cause of urethritis in men and cervicitis in women. Dysuria and mucopurulent/watery urethral discharge are common, but up to 50% of cases in men are asymptomatic. Microscopic examination of discharge will reveal leukocytes but no organisms because Chlamydia does not have sufficient peptidoglycan in the cell wall to take up Gram stain.
Diagnostic confirmation requires nucleic acid amplification testing (NAAT) of a swab from the site of infection (eg, urine, vaginal, endocervical, anal). Patients with Chlamydia urethritis are treated with a single dose of oral azithromycin or 7 days of oral doxycycline. All patients with C trachomatis infection should inform current and recent sexual partners so they can get tested and treated; otherwise, reinfection is common.
(Choices A and D) A single dose of azithromycin cures C trachomatis urethritis in most patients and is usually given in the office to ensure compliance. A 7-day course of oral doxycycline can also be used. Because this patient's symptoms resolved completely following azithromycin treatment, incorrect dosing and microbial resistance to azithromycin are unlikely. Most recurrent infections arise from sexual contact with an untreated partner.
(Choice B) Herpes simplex infection may reactivate and cause genital vesicular skin lesions. Urethritis may occur but is far less common than skin manifestations (and much rarer than gonococcal or chlamydial urethritis).
(Choice E) C trachomatis and Neisseria gonorrhoeae cause most cases of infectious urethritis in men. Although NAAT is required to diagnose C trachomatis infection, urethral swab Gram stain can quickly diagnose gonococcal urethritis (intracellular gram-negative diplococci). This patient's Gram stain showed leukocytes without organisms, which indicates nongonococcal urethritis; therefore, he was treated empirically for Chlamydia with azithromycin. Because his symptoms resolved completely with treatment, concurrent untreated infection is unlikely.
Educational objective:
Chlamydia trachomatis infection is often asymptomatic but may cause dysuria and mucoid discharge, particularly in men. Treatment with a one-time dose of azithromycin or 7 days of doxycycline is usually curative; however, current and recent sexual partners must receive testing and treatment to prevent reinfection.