I had pseudotrophomonas 9 months ago. I now have an elevated immature granulocyte count. I can it lie dormant then return?

Unlikely. Bacterial infections can linger, but usually if immature granulocytes are present due to infection, you are obviously ill. The more the blood is abnormal, the sicker the patient. If you have no infection signs or symptoms i would be concerned there is another cause of the blood problem. See a hematologist (blood specialist).