Combined use of QuantiFERON-TB Gold assay and chest computed tomography in a tuberculosis outbreak.
OBJECTIVE
To evaluate the value of the QuantiFERON-TB Gold (QFT-G) assay and chest computed tomography (CT), in addition to the conventional use of the tuberculin skin test (TST) and chest radiography (CXR), in a contact investigation of a tuberculosis (TB) outbreak.


METHODS
In a contact investigation of a TB outbreak in a high school, TST and CXR were performed on all 1044 employees and students. QFT-G was performed on TST-positive subjects, and CT on QFT-G-positive subjects and students with TST > or =20 mm.


RESULTS
TST was positive in 388 subjects (37.2%), while QFT-G was positive in 7.6% (30/394). CXR showed abnormal findings suggestive of TB in 10 (1.0%) subjects, all of whom were TST-positive and six of whom were QFT-G-positive. Findings suggestive of active TB were noted in 17 (32.7%) of 52 subjects by CT. Collectively, among 21 (1.1%) TB patients, all were TST-positive, 12 (57.1%) were QFT-G-positive and active TB was diagnosed by CT, and not by CXR, in 11 subjects.


CONCLUSIONS
Compared to the conventional approach, the additional use of QFT-G in TST-positive subjects and chest CT in subgroups with a high probability of infection was found to be more effective in the differentiation between active TB, latent TB and non-infected subjects in a contact investigation.
Lew
W J
WJ
The Korean Institute of Tuberculosis, Seoul, Korea.
Jung
Y J
YJ
Song
J-W
JW
Jang
Y M
YM
Kim
H-J
HJ
Oh
Y-M
YM
Lee
S D
SD
Kim
W S
WS
Kim
D S
DS
Kim
W D
WD
Shim
T S
TS
D000293:Adolescent; D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007723:Korea / Q000453:epidemiology; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D013902:Radiography, Thoracic / Q000379:methods*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014373:Tuberculin; D014374:Tuberculin Test / Q000379:methods*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000453:epidemiology*; D055815:Young Adult
D014373:Tuberculin