Is it possible this isn't active TB?

My 21 month old son, adopted from Kaluga Russia in 7/03 had a positive PPD with induration of 10mm.  His chest x-ray results are "PA & lateral views of the chest demonstrates prominence of the hilum bilaterally worse on the left side with suspicion of early infiltrate in the right middle lobe.  The costophrenic angles are clear.  There is no pneumothorax.  The bony thorax is unremarkable."  The Impression states "Findings suggestive of left greater than right hilar adenopathy and perhaps an early infilitrate in the area of the right middle lobe.  Follow up to complete clearing and correlation clinically suggested."

He showed no symptoms what so ever, but was x-rayed because of the PPD result.  He has been on INH, rifampin, EMB, PZA 5xs/week and amikacin 2xs/week for the past 8 weeks.  He has gained a total of 1 lb 11 ozs since the start of that treatment.  His smears and culture have come back negative.  The health dept has stated concern with the possibility of drug resistence based on the fact that Kaluga Russia is known to have a 40% occurence of INH resistence.  My son also has renal tubular acidosis and so the PZA and amikacin really scare me.  

Is there any chance that this isn't TB?  Are they over doing it by including the amikacin in his treatment?  Should I request a CT scan?

[National Jewish]

Given the appearance of the chest x-ray I would have thought tuberculosis (TB) was the likely diagnosis.  They could consider stopping the PZA (pyrazinamide) and Amikin