Combining the Capilia TB assay with smear morphology for the identification of Mycobacterium tuberculosis complex.
METHODS
Many hospitals in Taiwan use the fully automated BACTEC Mycobacterial Growth Indicator Tube (MGIT) 960 system to identify mycobacteria in clinical specimens, while the labour-intensive BD ProbeTec ET (CTB) system or biochemical methods are used to identify Mycobacterium tuberculosis complex (MTC) in mycobacterially positive BACTEC cultures.


OBJECTIVE
To evaluate whether the Capilia TB assay can be used to replace the BD ProbeTec ET (CTB) system or biochemical methods for identifying MTC in BACTEC cultures.


METHODS
Mycobacterially positive BACTEC cultures were collected and MTC in the cultures was identified using biochemical methods. MTC was identified using serpentine cording in smears, the Capilia TB assay or the BD ProbeTec ET (CTB) system, and the results were compared.


RESULTS
Using 233 mycobacterially positive BACTEC cultures, the sensitivity and specificity of identification of the Capilia TB assay were respectively 96.9% and 98.6%, while those of the BD ProbeTec ET (CTB) system were respectively 99.4% and 97.3%. Combining the Capilia TB assay with serpentine cording in smears led to 100% specificity for intersected results and 100% sensitivity for combined results.


CONCLUSIONS
The Capilia TB assay can be used to identify MTC in BACTEC cultures. By combining the assay with serpentine cording in smears, false-positives and -negatives may be reduced.
Shen
G-H
GH
Department of Internal Medicine, Division of Respiratory and Critical Care Medicine, Taichung Veterans General Hospital, Taichung, Taiwan, Republic of China.
Chen
C-H
CH
Hung
C-H
CH
Wu
K-M
KM
Lin
C-F
CF
Sun
Y-W
YW
Chen
J-H
JH
D000942:Antigens, Bacterial / Q000032:analysis / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000032:analysis / Q000302:isolation & purification; D002845:Chromatography / Q000379:methods; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000145:classification* / Q000276:immunology; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C080865:MPB64 protein, Mycobacterium; D011933:Reagent Kits, Diagnostic