Infections and Inflammatory Diseases of the Urinary Tract
This domain tests classification of urinary infection, antimicrobial choice under resistance pressure, and recognition of the emergencies. The recurring theme is distinguishing uncomplicated from complicated infection and knowing when imaging or drainage is mandatory.
Classification and uncomplicated cystitis
- Uncomplicated cystitis: non-pregnant woman, no structural or functional abnormality. First-line agents are nitrofurantoin for 5 days, fosfomycin single dose or pivmecillinam; fluoroquinolones are reserved because of resistance and collateral damage.
- Complicated infection: male sex, pregnancy, catheter, obstruction, stone, immunosuppression, renal impairment. Send culture before antibiotics and treat 7-14 days.
- Asymptomatic bacteriuria is treated only in pregnancy and before urological surgery involving mucosal trauma; treating it otherwise selects resistant organisms.
Upper tract and male genital infection
- Acute pyelonephritis: fluoroquinolone or third-generation cephalosporin, intravenous then oral for 10-14 days; image with CT if no response in 48-72 hours, and decompress an obstructed infected kidney.
- Prostatitis, NIH categories: acute bacterial (I), chronic bacterial (II), chronic pelvic pain syndrome (III), asymptomatic inflammation (IV). Acute prostatitis needs 2-4 weeks of a fluoroquinolone; chronic bacterial needs 4-6 weeks.
- Epididymo-orchitis under 35 years is usually chlamydia or gonorrhoea: ceftriaxone 500 mg intramuscularly once plus doxycycline for 10-14 days, with partner notification. Older men or those with uropathy get a fluoroquinolone and investigation of obstruction.
Emergencies and special situations
- Fournier gangrene is polymicrobial: resuscitation, broad-spectrum cover including anaerobes, and immediate surgical debridement; repeated look-backs are routine.
- Urinary tuberculosis: sterile pyuria, early morning urine cultures, 6 months of rifampicin, isoniazid, pyrazinamide and ethambutol.
- Catheter-associated infection: remove or change the catheter and culture a fresh sample.
Worked example
A 28-year-old man has dysuria, urethral discharge and unilateral scrotal pain with a positive chlamydia nucleic acid amplification test. This is sexually transmitted epididymitis. Treat with ceftriaxone 500 mg intramuscularly once plus doxycycline 100 mg twice daily for 10-14 days, treat the partner, and avoid aspiration unless an abscess forms. Scrotal ultrasound is indicated if torsion cannot be excluded clinically.
Traps that cost marks
Using nitrofurantoin for pyelonephritis, where tissue levels are inadequate; treating asymptomatic bacteriuria outside pregnancy and pre-operative mucosal surgery; missing torsion when labelling scrotal pain as epididymitis; failing to image or drain an obstructed infected kidney; ignoring local fluoroquinolone resistance.