[TB-test in the diagnosis of "closed" tuberculosis of the urinary tract. Preliminary study]

Tuberculosis (TBC) is a disease that is found throughout the world with a particularly high incidence in under developed countries. Genitourinary tuberculosis has been reported in 8-10% of all cases in developed countries and in 20% in Third World countries. This study aimed to describe a method of diagnosis applicable to so-called "closed" forms of tuberculosis affecting the urinary tract, namely those with negative results for KB bacteriological and culture assay, but in which suspected diagnosis based on clinical grounds and diagnostic procedures call for further analysis; these forms account for 10% of the total cases.

A prospective study was carried out in order to tritade the antigenic fraction A60 of the group of thermostable macromolecular antigens (TMA); the latter belong to the pool of liposoluble antigens forming the cell wall and represent the main component of tuberculin and purified protein derivative (PPD). The identification and assay of antigen A60, which can stimulate both the antibody and cell-mediated response, was performed using the ELISA method in order to identify IgG and IgM specific antibodies (TB-test). Twenty-nine patients were selected (11 males, 18 females) with a clinical history of recurrent symptomatic manifestations of upper and lower urinary tract infections resistant to common antibiotic treatment. Urinary tests showed that 96.5% of patients presented an acid urinary pH associated with pyuria, and the urographic imaging revealed calico/pyelic lesions of the excretory tracts.

Seven patients (24%) showed a form of urinary TBC of an areactive type (AA) or with intermediate reactivity (RI.AI); six patients (20.64%) showed reactive TBC or in the process of resolution; fifteen patients (51.6%) were negative to the TB-test, and after one year's follow-up still showed no positivity to assays for Koch's bacillus.

The authors affirm that the TB-test, a rapid and relatively inexpensive diagnostic method, is a valid aid for the diagnosis of "closed" forms of urinary tract TBC.