TABLE 9

CDC recommendations for interpretation of results of tuberculosis nucleic acid amplification tests on respiratory specimensa

AFB smear resultTB NAAT resultInterpretation
PositivePositivePresumed pulmonary TB
Begin anti-TB therapy while awaiting culture and susceptibility results
NegativePositiveConsider performing NAAT on a second specimen to confirm results
Consistent with pulmonary TB but less infectious than AFB smear-positive TB
Use clinical judgment regarding beginning anti-TB therapy
PositiveNegativeRule out inhibition by using an internal amplification control
Test additional specimen(s) by NAAT
Consistent with the presence of NTM if all NAAT results are negative
Use clinical judgment regarding beginning anti-TB therapy
NegativeNegativeRule out inhibition by using an internal amplification control
Multiple negative AFB smears and multiple negative NAAT results, in combination with other requirements, support discontinuation of airborne isolation
Use clinical judgment regarding beginning anti-TB therapy
  • a See references 105, 106, and 342.