A 19-year-old man comes to the emergency department due to dysuria and scrotal pain. The patient first noticed discomfort with urination and a watery urethral discharge 3 days ago. Yesterday, he developed pain on the left side of the scrotum while sitting in class. Vital signs are normal. On examination, tender swelling is present along the posterior aspect of the left testis, which is otherwise normal in size and position. Diagnostic testing reveals Chlamydia trachomatis as the sole causative pathogen. Which of the following additional results are most consistent with this patient's diagnosis?

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11ec160b_3825_b7c5_9249_9d678ed7bee4_MD0001_00 This patient has infectious urethritis and epididymitis due to Chlamydia trachomatis. C trachomatis urethral infections are often asymptomatic but patients may develop dysuria and scant, watery discharge; deeper spread to the epididymis is typically marked by scrotal pain with tenderness along the posterior aspect of the testis. Laboratory results in patients with infectious urethritis due to C trachomatis are as follows: Pyuria: Urine dipstick testing will show positive leukocyte esterase, and urine Gram stain will reveal ≥10 white blood cells/hpf (Choice E). Poor Gram staining: Gram stain of urethral swab can quickly diagnose Neisseria gonorrhoeae infection (intracellular gram-negative diplococci); however, organisms will not be seen in the setting of C trachomatis or Mycoplasma genitalium infection because these pathogens do not have sufficient peptidoglycan in their cell wall to pick up Gram stain. Negative urine culture: Because C trachomatis is an obligate intracellular pathogen, it cannot be grown on traditional culture medium; therefore, urine and genital swab cultures will be negative. The microbial diagnosis of C trachomatis infection is generally established with urine (or cervical) nucleic acid amplification testing. (Choice A) Positive urine white blood cell, Gram stain, and urine culture results are typical of a urinary tract infection caused by Escherichia coli or Klebsiella pneumoniae. However, obligate intracellular parasites such as C trachomatis are not seen on Gram stain or easily cultured. (Choice B) Patients with N gonorrhoeae infection usually have pyuria, but have a negative urine culture because a specialized medium (eg, Thayer-Martin agar) is typically required to grow the organism. Gram stain of urethral discharge would show gram-negative intracellular diplococci. (Choice D) Positive urine Gram stain and culture with no pyuria may be seen in some patients with asymptomatic bacteriuria, a typically benign condition except in select situations (eg, pregnancy). Educational objective: Urinalysis in patients with Chlamydia trachomatis infection classically shows sterile pyuria (positive urine white blood cells, no bacteria on Gram stain, no growth on culture) because the C trachomatis bacterium is an obligate intracellular parasite with minimal peptidoglycan in its cell wall. The diagnostic test of choice is nucleic acid amplification testing. __________ References: Urethritis. (http://www.ncbi.nlm.nih.gov/pubmed/30725967)

A 19-Year-Old Man Comes to the Emergency Department Due to Dysuria