Impact of the Gen-Probe Amplified MTD® Test on tuberculosis diagnosis in children.
OBJECTIVE
To evaluate the performance of the Gen-Probe Amplified MTD® Test (AMTD) for childhood tuberculosis (TB) diagnosis compared to conventional culture.


METHODS
We retrospectively studied 121 childhood cases (73 males; median age 7 years, range 1-16). Pulmonary samples  (104/152, 68%) included gastric aspirates (n = 53), induced sputum samples (n = 43), bronchial aspirates and bronchoalveolar lavage (n = 8). Extra-pulmonary samples (48/152, 32%) included lymph nodes (n = 34) and other sterile fluids (n = 14). Specimens were  examined using acid-fast bacilli (AFB) microscopy, AMTD and bacterial culture using BACTEC™ MGIT™ 960 and Löwenstein-Jensen (LJ) media.


RESULTS
A clinical diagnosis of TB was made in 50/121 (41%) children (43/50 pulmonary disease). AFB microscopy was positive in 6%; Mycobacterium  tuberculosis was recovered by culture from 16/50 (32%) and AMTD was positive in 29/50 (58%). AMTD sensitivity, specificity, positive predictive value and negative predictive value compared to culture were respectively 100%, 85%, 50% and 100%. For pulmonary vs. extra-pulmonary disease,  the performance of AMTD compared to culture was respectively 100%, 77%, 46% and 100% vs. 100%, 97.5%, 75% and 100%.


CONCLUSIONS
Nucleic acid amplification tests are more sensitive and very specific methods for the rapid detection of M. tuberculosis. The AMTD technique increases  TB detection in children compared to conventional culture.
National Reference Laboratory for Mycobacteria, Sotiria Chest Diseases Hospital, Athens, Greece. dpapaventsis@yahoo.gr
D
D
Papaventsis
P
P
Ioannidis
S
S
Karabela
S
S
Nikolaou
G
G
Syridou
I
I
Marinou
E
E
Konstantinidou
V
V
Amanatidou
N
N
Spyridis
S
S
Kanavaki
M
M
Tsolia
D000293:Adolescent; D001431:Bacteriological Techniques; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014376:Tuberculosis / Q000175:diagnosis* / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000382:microbiology