A 26-year-old man comes to the physician with a 1-week history of dysuria and increased urinary frequency. He has had multiple sexual partners in the past month and is inconsistent with condom use. His temperature is 37.1 C (98.9 F), blood pressure is 110/70 mm Hg, and pulse is 68/min. Mucopurulent discharge is seen at the urethral meatus. Urinalysis shows the following:
Blood Negative Glucose Negative Ketones Negative Leukocyte esterase Positive Nitrites Negative White blood cells 50-100/hpf Red blood cells 0-1/hpf Bacteria None
Gram stain of the discharge shows no bacteria. Culture of the discharge and urine show no growth after 48 hours of incubation. Which of the following is the most likely diagnosis?
Infectious urethritis in men | |
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*GU + uncertain Chlamydia status is also treated with ceftriaxone + doxycycline. GU = gonococcal urethritis. | |
This patient is sexually active and has dysuria, pyuria (white blood cells >10/hpf), urinary frequency, and urethral discharge; these symptoms are concerning for urethritis. There was no growth on the Gram stain and urine culture ("culture-negative" urethritis), which should raise concern for chlamydial urethritis. Chlamydia trachomatis is a common cause of urethritis in men. It cannot be visualized in Gram-stained material or recovered in conventional culture. The diagnosis can be made with nucleic acid amplification testing of a first-catch urine sample without pre-cleaning the genital area. The treatment of choice is azithromycin or doxycycline.
(Choices A and B) Patients with acute bacterial cystitis have dysuria, urinary frequency, suprapubic discomfort, bacteriuria, and pyuria. Fever, flank pain, and costovertebral tenderness are present if the infection spreads beyond the bladder (pyelonephritis). Mucopurulent urethral discharge is not found. Urine culture is the gold standard for diagnosing urinary tract infection.
(Choice D) Gonococcal urethritis presents in a similar fashion to chlamydial urethritis. Neisseria gonorrhoeae is also very common and infection often occurs simultaneously with C trachomatis. Gram stain shows the gram-negative cocci of gonococcus in 95% of cases of gonococcal urethritis, making this diagnosis unlikely.
(Choice E) Trichomoniasis is usually asymptomatic in men and is an uncommon cause of urethritis. Although motile trichomonads are typically seen on the wet mount prep in women, microscopy is insensitive in men.
Educational objective:
In the absence of identifiable bacteria on culture or Gram stain, a mucopurulent urethral discharge in a patient who is sexually active suggests chlamydial urethritis. Nucleic acid amplification testing confirms the diagnosis.