Anergy is like that...
But not doing it, in this situation, is negligent
TB can still be present, with a (-) TB skin test,
in immunocompromised patients
when we worked in Africa, all kids got BCg so had a mildly positive test. A negative test meant anergy.
The question is if she ever had BCG...
and the article is unclear if she was a case of primary or secondary tb...in primary TB it spreads before the skin test turns positive, in secondary TB, it is usually positive but can be negative from anergy.