144 GU Infectious disease and getting more questions right
Urethritis
Inflammation or infection of the urethra, usually from a sexually transmitted infection (STI).
Most common pathogens: Chlamydia trachomatis and Neisseria gonorrhoeae.
Can also result from chemical irritation or catheter use.
Risk Factors
Multiple or new sexual partners
Unprotected intercourse
Prior STI history
Men under 35 years old
Clinical Presentation
Dysuria, burning, or itching at urethral meatus
Urethral discharge:
Clear or mucoid → Chlamydia
Thick yellow-green → Gonorrhea
Urethral redness or irritation
The question stem would likely describe a young sexually active man with dysuria and discharge after unprotected sex.
Diagnostics
NAAT (nucleic acid amplification test): Urethral swab or first-catch urine → most sensitive for Chlamydia and Gonorrhea.
Urinalysis: Pyuria without bacteriuria (“sterile pyuria”) — WBCs in urine but no bacterial growth due to intracellular organisms like Chlamydia.
Consider Trichomonas vaginalis or Mycoplasma genitalium if persistent symptoms.
Screen for HIV and syphilis.
Treatment
Empiric therapy for both C. trachomatis and N. gonorrhoeae:
Ceftriaxone 500 mg IM single dose
plus Doxycycline 100 mg PO twice daily for 7 days
If doxycycline contraindicated → Azithromycin 1 g PO single dose
Treat all sexual partners.
Abstain from sexual activity for 7 days after treatment.
Retest at 3 months due to high reinfection rate.
Exam Keys
Dysuria + urethral discharge = Urethritis (STI until proven otherwise).
Gonorrhea: Purulent yellow-green discharge.
Chlamydia: Clear or mucoid discharge.
Sterile pyuria: WBCs present but no bacterial growth → Chlamydia.
Always treat both pathogens empirically.
Urinary Tract Infection (Cystitis)
Infection of the bladder (lower urinary tract) most often caused by Escherichia coli.
Common in women due to short urethra and proximity to anus.
Classified as uncomplicated (healthy, nonpregnant women) or complicated (men, pregnancy, diabetes, obstruction, catheters).
Risk Factors
Female sex, sexual activity, diaphragm or spermicide use.
Postmenopausal estrogen loss, pregnancy, diabetes.
Indwelling catheters or urinary obstruction (BPH, stones).
Clinical Presentation
Dysuria, frequency, urgency, suprapubic pain, hematuria, cloudy urine.
No systemic symptoms (no fever, chills, or flank pain).
If fever or costovertebral tenderness → think pyelonephritis.
The question stem would likely describe a young woman with burning urination, frequency, and no fever.
Diagnostics
Urinalysis: Pyuria, positive leukocyte esterase, and nitrites (Gram-negative organisms).
Urine culture: >100,000 CFU/mL of a single organism confirms diagnosis.
Urine dipstick: Often sufficient in uncomplicated cases.
Men or recurrent infections: Consider ultrasound to assess for obstruction or stones.
Treatment
Uncomplicated: Nitrofurantoin, Trimethoprim-Sulfamethoxazole (TMP-SMX), or Fosfomycin.