''Just follow the book, don't look for magic fixes to get you off the hook. Do the work.'' Dr.D.'98 DNA mt/Haplo H; Y-chrom/J2(M172);ESTJ The harder you are on yourself, the easier life will be on you!
Tuberculin is a glycerol extract of the tubercle bacillus. Purified protein derivative (PPD) tuberculin is a precipitate of species-nonspecific molecules obtained from filtrates of sterilized, concentrated cultures.
It's a test to see if you have TB.
If a person has had a history of a positive tuberculin skin test, or had a recent tuberculin skin test (within one year), another skin test should be used.