Non-Gonococcal Urethritis (NGU)

Definition

Etiology / Causative Organisms

• Elementary body - the infectious extracellular form; enters host cells via receptor-mediated endocytosis
• Reticulate body - the metabolically active intracellular form; replicates using host cell energy, has tropism for columnar epithelial cells
• Robbins & Kumar Basic Pathology; Campbell-Walsh Urology

Clinical Features

• Dysuria and a white/mucopurulent urethral discharge (appears up to 6 weeks after sexual contact)
• Discharge is typically scant and mucoid - less purulent than gonococcal urethritis
• Urine appears clear but may contain "threads" or pus cells
• Often asymptomatic - up to 30% of cases
• Coinfection with gonorrhea is common

• Usually asymptomatic
• Can present as vaginal discharge, urethritis, cervicitis, or pelvic inflammatory disease (PID)

• Epididymitis (common in men)
• Urethral stricture (late complication)
• Prostatitis (prostate may act as a reservoir, causing relapse in men)
• Reactive arthritis (Reiter syndrome): urethritis + conjunctivitis + arthritis
• Neonatal conjunctivitis (most common) and pneumonia if transmitted during vaginal birth
• PID, salpingitis, infertility in women
• Bailey & Love's Surgery; Campbell-Walsh Urology; Robbins & Kumar

Diagnosis

• Gram stain of urethral smear showing >5 neutrophils/high-power field with absence of gram-negative intracellular diplococci (which would suggest gonorrhea)
• First-catch urine with leukocyte esterase positive, or >10 WBCs/hpf on microscopy

• NAAT (Nucleic Acid Amplification Test) on first-catch urine or urethral swab - gold standard for C. trachomatis, N. gonorrhoeae, T. vaginalis, and M. genitalium; highest sensitivity and specificity
• Wet mount microscopy - can identify T. vaginalis but is less sensitive than NAAT
• Gonorrhea must be excluded before diagnosing NGU

• Rosen's Emergency Medicine; Bailey & Love's; Smith & Tanagho Urology

Treatment

First-Line NGU Treatment

• If gonorrhea has NOT been ruled out by NAAT: add ceftriaxone 500 mg IM single dose empirically
• Treat both patient and sexual partners; abstain from intercourse until both are fully treated

Alternative Regimens (allergy/intolerance)

• Erythromycin base 500 mg PO QID x 7 days
• Erythromycin ethylsuccinate 800 mg PO QID x 7 days
• Levofloxacin 500 mg PO once daily x 7 days
• Ofloxacin 300 mg PO twice daily x 7 days

If Trichomonas is identified/suspected

• Metronidazole 2 g PO single dose OR Tinidazole 2 g PO single dose

Persistent / Recurrent NGU

1. If non-compliant or re-exposed to untreated partner -> repeat initial regimen
2. If failed doxycycline -> Azithromycin 1 g single dose
3. If failed azithromycin -> Moxifloxacin 400 mg PO daily x 7 days
4. Rule out T. vaginalis (send urine NAAT); treat with metronidazole/tinidazole if positive
5. Consider chronic pelvic pain syndrome if pelvic pain is prominent and no pathogen identified

• Smith & Tanagho General Urology; Campbell-Walsh Urology; Rosen's Emergency Medicine

Follow-Up

• Repeat testing at 3 months after treatment regardless of partner treatment status (high reinfection rates)
• Test of cure NOT required if recommended regimen completed (residual nucleic acids can give false positives within 3 weeks)
• Notify and treat all sex partners with contact in the 60 days preceding symptom onset

Key Distinguishing Points: NGU vs Gonococcal Urethritis