Table 4. Tuberculin skin test (TST) results of 8 subjects who were not required to receive chemoprophylaxis and developed tuberculosis during the follow-up period (cases with false-negative test results).
| Number of false-negative case |
Exposure group* |
Sex | Age (year) | Erythema on the TST at entry into school (Time 1) (mm) |
Reactions on the TST in the contact investigation (Time 2) (mm) |
Increase in the erythema from Time1 to Time2 (mm) |
|
| Erythema | Induration | ||||||
| 1 | 2 | Female | 15 | 3 | 24 | 17 | 21 |
| 2 | 2 | Male | 15 | 12 | 25 | 15 | 13 |
| 3 | 2 | Female | 13 | 16 | 16 | 11 | 0 |
| 4 | 3 | Male | 15 | 6 | 23 | 15 | 17 |
| 5 | 3 | Male | 15 | 13 | 26 | 11 | 13 |
| 6 | 3 | Female | 15 | 23 | 6 | 0 | -17 |
| 7 | 4 | Female | 13 | 6 | 22 | 19 | 16 |
| 8 | 4 | Female | 13 | 15 | 14 | 13 | -1 |
* : Group 2, students who shared special classes or extracurricular activities with the case; Group 3, third-grade students after excluding those who belonged to exposure group 1 and group 2; Group 4, first- or second-grade students after excluding those who belonged to exposure group 2.