Differential Diagnosis for Dysuria, Penile Discharge, and No Bacterial Growth
Single Most Likely Diagnosis
- Urethritis due to Chlamydia trachomatis or Mycoplasma genitalium: These sexually transmitted infections (STIs) are common causes of dysuria and penile discharge in men, especially in the absence of bacterial growth on standard cultures, as they may require specialized media or nucleic acid amplification tests (NAATs) for detection.
Other Likely Diagnoses
- Herpes Simplex Virus (HSV) infection: Although primarily known for causing genital ulcers, HSV can also lead to dysuria and discharge, especially if the ulcers are inside the urethra.
- Urethral stricture or other anatomical issues: Conditions that cause narrowing or obstruction of the urethra can lead to symptoms of dysuria and possibly discharge due to urinary retention or infection.
- Non-gonococcal, non-chlamydial urethritis (NGU): This category includes infections caused by other organisms such as Ureaplasma urealyticum, Trichomonas vaginalis, and adenovirus, which can cause similar symptoms.
Do Not Miss Diagnoses
- Gonorrhea with resistant strains: Although bacterial cultures may not show growth, gonorrhea caused by antibiotic-resistant strains must be considered, especially given the rising rates of resistance.
- Syphilis: Primary syphilis can cause a painless urethral discharge and dysuria, and missing this diagnosis can have significant long-term health implications.
Rare Diagnoses
- Reiter's syndrome (Reactive Arthritis): A form of reactive arthritis that can occur after certain bacterial infections, including STIs, and is characterized by a combination of arthritis, urethritis, and conjunctivitis.
- Behçet's disease: A rare condition that can cause a wide range of symptoms including genital ulcers, urethritis, and eye inflammation, among others.
- Urethral foreign body: Although rare, the presence of a foreign body in the urethra can cause obstructive symptoms, discharge, and dysuria.