All in the Stream

The two-month initiation phase of treatment with four antituberculosis drugs should begin while drug susceptibility tests are pending. Potential hepatotoxicity should be closely monitored, ideally by a clinician with experience treating tuberculosis in patients with existing liver disease. As a general precaution, alcohol should be avoided as should medications such as acetaminophen that are known to be hepatotoxic. Urology follow-up is also needed because about one-third of tuberculous ureteral strictures treated initially with percutaneous nephrostomy do not resolve with antituberculosis therapy.

The patient was started on weight-based antituberculosis treatment with four antimicrobial agents (rifampin, ethambutol, pyrazinamide, and isoniazid). He was seen in the infectious disease clinic two weeks later; his fever had resolved, and his liver function tests showed normalization of AST and LDH as well as a 45% reduction in his GGT and alkaline phosphatase levels. Two months following discharge, a nuclear medicine radionuclide angiogram renal flow scan showed normal right kidney function. The right nephrostomy tube was subsequently removed. He continued to have left kidney outflow obstruction due to a residual ureteral stricture (Figure 4). Repeat cystoscopy and attempted left ureteral stenting was unsuccessful. The left nephrostomy tube remained in place.

According to the Centers for Disease Control, in 2017, 10 million people became sick with TB, and there were 1.3 million TB-related deaths worldwide with 9,150 cases reported in the United States. Extrapulmonary TB (EPTB) constitutes 10% of all TB cases globally.^1-4 GUTB is the second most common form of EPTB after lymph node TB, and it occurs in up to 20% of all pulmonary TB cases.^2,3

Mycobacteria reach the genitourinary (GU) tract via hematogenous spread during primary infection or reactivation of TB. This leads to cortical and medullary lesions, which can heal spontaneously or eventually (average of 22 years) rupture into the tubules and onto the collecting system, ureters, and bladder.^5,6 Spread to the ureter and bladder leads to multiple ureteral strictures and contracture of the bladder with disruption of the ureterovesical junction (UVJ), which causes hydroureter and hydronephrosis.⁷ Unilateral kidney involvement is most common, but bilateral involvement can occur following exacerbated hematogenous spread, particularly in immune deficient patients. Bilateral kidney involvement is also possible from retrograde spread to the good kidney due to bladder contracture and UVJ disruption.^8,9 Distal infection can involve all aspects of the male and female genital tracts, but urethral strictures are extremely rare.^10,11

GUTB affects males more than females (2:1) and presents insidiously at 40 to 60 years of age.¹² Other risk factors for TB include birth in TB endemic areas, prior TB infection, immunosuppression, malnutrition, severe systemic disease, diabetes, and cirrhosis. It is crucial to assess these risk factors when creating and refining differential diagnoses. Many patients have hematuria and sterile pyuria as incidental initial findings. The most common symptoms arise from bladder involvement, including frequency, urgency, and dysuria. Low back pain and gross hematuria are also common, but fever and constitutional symptoms are uncommon.¹⁰ Bilateral ureteral strictures can lead to obstructive renal failure, and involvement of the genital tracts can lead to pelvic or scrotal pain, swelling, and fistula formation.¹⁰

Diagnosis involves the demonstration of TB bacilli in urine or GU tissue. The urinalysis reveals hematuria and sterile pyuria.¹³ Urine AFB stains are positive in 52% of cases but are not diagnostic as nontuberculous mycobacteria may also cause a positive test result.^13,14 Urine cultures for Mycobacterium tuberculosis are positive in up to 90% of cases after six to eight weeks. As many as three to six morning urine samples are required to achieve diagnostic accuracy.^10,14 Urine PCR for Mycobacterium tuberculosis has 96% sensitivity and up to 98% specificity,¹⁴ while PCR on GU tissue has a sensitivity of 88% and specificity of 87%.¹⁵ The rapid nucleic acid amplification assay Xpert MTB/RIF in urine has a sensitivity of 83%, and specificity of 98%.¹⁶ Imaging is required to evaluate for obstruction, and the CT scan is abnormal in up to 90% of cases, showing multiple ureteral stenoses, hydroureter and hydronephrosis, and a contracted bladder.^10,17

GUTB is treated with standard antituberculosis regimens.¹⁸ Patients with urinary obstruction benefit from ureteral stenting or percutaneous nephrostomy, bladder diversion, or ureteral reconstruction surgery. Unilateral nephrectomy for a nonfunctioning kidney with extensive disease is occasionally required.¹⁹ Following treatment, relapse occurs in up to 6% of patients over five years, and long-term follow-up with urine cultures and PCR every six months is recommended.^10,20 Appropriate screening and treatment for latent tuberculosis infection greatly reduces the risk of reactivation GUTB.

This patient presented with features of an infection, which, combined with his history of renal stones and his urinalysis, led to an appropriate suspicion of and empiric treatment for an upper UTI. Given the AKI and nephrolithiasis, imaging was done to exclude obstruction. The CT finding of bilateral hydroureters and hydronephrosis absent an obstructing stone or mass or abnormal bladder was the initial clue that this was not a typical bacterial infection and that there was likely an underlying infectious pathologic process such as TB involving the GU tract diffusely. The care team treated the patient as an individual with fever and sterile pyuria in the context of multiple urinary tract strictures and an initial unrevealing infectious diagnostic workup. They recognized that the clues to the ultimate diagnosis of GUTB were all in the stream.