He’s a “tuberculin converter.” which means he has been infected with TB since his last skin test.
A tuberculin converters skin test will be positive. meaning he has been exposed to an infected with TB and now has a cell-mediated immune response to the skin test. The clients blood and x-ray results may stay negative. It doesnt mean the infection has advanced to the active stage. Because his x-ray is negative. he should be monitored every 6 months to see if he develops changes in his x-ray or pulmonary examination. Being a seroconverter doesnt mean the TB has gotten into his bloodstream; it means it can be detected by a blood test.