Genitourinary tuberculosis: sterile pyuria and ureteral stricture

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A previously healthy 32-year-old woman who recently moved from Mexico has several months of dysuria, urinary frequency, and flank pain with persistent pyuria; multiple urine cultures have been negative. She has no cough, dyspnea, fever, weight loss, or sick contacts. Urinalysis shows trace protein, pH 4.5, 2+ leukocyte esterase, >50 WBC/hpf, and 10–15 RBC/hpf. CT of the abdomen and pelvis shows a left ureteral stricture with segmental dilations. What is the most appropriate next step?

  1. A.Anti-tuberculous therapy
  2. B.Chest x-ray
  3. C.Purified protein derivative (PPD) testing
  4. D.Urine acid-fast bacillus (AFB) microscopy and cultureCorrect

Explanation

The most appropriate next step is urine acid-fast bacillus microscopy and mycobacterial culture. This young woman from a tuberculosis-endemic region has months of dysuria, frequency, and flank pain with sterile pyuria (more than 50 WBCs per high-power field with repeatedly negative routine cultures), hematuria, an acidic urine, and a ureteral stricture with segmental dilation, giving the beaded ureter appearance typical of genitourinary tuberculosis. Genitourinary disease is among the most common forms of extrapulmonary tuberculosis and results from hematogenous seeding of the kidney, often years after primary infection, so most patients have no active pulmonary symptoms and many have a normal chest radiograph. Granulomatous inflammation descends through the collecting system, producing papillary necrosis, calyceal distortion, ureteral strictures, and a contracted bladder. Diagnosis requires microbiological confirmation. At least three, and preferably five, consecutive first-morning urine samples should be sent for AFB smear, mycobacterial culture, and nucleic acid amplification testing; culture remains the reference standard and provides drug susceptibility results, which guide a 6-month regimen. Early recognition matters because ureteral strictures can cause obstruction and loss of kidney function, sometimes requiring stenting. A chest radiograph is reasonable as part of the evaluation to look for active or prior pulmonary disease, but it is often normal in genitourinary tuberculosis and cannot establish the diagnosis. PPD testing, or an interferon-gamma release assay, detects tuberculosis infection but cannot distinguish latent from active disease. A positive result is expected in many people from endemic regions, and a negative result does not exclude genitourinary tuberculosis. Starting anti-tuberculous therapy empirically before obtaining urine cultures would compromise microbiological confirmation and drug susceptibility testing. In a stable outpatient, specimens should be collected first, and therapy started once samples are obtained or the diagnosis is supported.

Why each option

A.
Starting empiric anti-tuberculous treatment before collecting urine specimens sacrifices microbiological confirmation and drug susceptibility testing in a clinically stable outpatient.
B.
A chest radiograph is often normal in genitourinary tuberculosis and cannot establish the diagnosis, although it is reasonable as part of the evaluation.
C.
Skin or interferon-gamma testing cannot distinguish latent from active disease, is often positive in people from endemic regions, and a negative result does not exclude disease.
D.
Correct. Sterile pyuria, hematuria, acidic urine, and a beaded ureteral stricture suggest genitourinary tuberculosis, confirmed by serial first-morning urine AFB smear and culture.

Reference: Nahid P, Clin Infect Dis 2016 (ATS/CDC/IDSA guidelines for treatment of drug-susceptible tuberculosis); Figueiredo AA, Microbiol Spectr 2017 (urogenital tuberculosis)

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