Bead capture increases the sensitivity of sputum microscopy for the diagnosis of tuberculosis in Beijing, China.
BACKGROUND
A review of the scientific literature concluded that indirect smear can improve detection of TB in sputum compared to direct smear. However few laboratories have access to centrifugation in order to perform indirect smear. This study investigated whether an alternative method of magnetic bead concentration could enhance diagnosis of TB in China in laboratories which only perform direct smear microscopy.


METHODS
A total of 129 sputum samples were investigated by direct smear microscopy, microscopy after TB-Bead extraction and by solid and liquid culture.


RESULTS
Direct smear had a sensitivity of 40% by Ziehl-Neelsen (ZN) and 45% by auramine compared to combined culture results. After TB-Bead extraction, this increased to 65% for ZN and 70% for auramine.


CONCLUSIONS
Magnetic bead concentration of mycobacteria from sputum led to a significant improvement (p<0.05) in the sensitivity of microscopy compared with direct smear.
National Clinical Laboratory on Tuberculosis, Beijing Key Laboratory on Drug-resistant Tuberculosis Research, Beijing Tuberculosis and Thoracic Tumor Institute, Beijing Chest Hospital, Capital Medical University, Beijing China 101149.
Xiaobo
X
Wang
Liping
L
Zhao
Xia
X
Yu
Yunxu
Y
Li
Yifeng
Y
Ma
Lingling
L
Dong
Hairong
H
Huang
D002681:China / Q000453:epidemiology; D006801:Humans; D008280:Magnetics / Q000379:methods; D008853:Microscopy / Q000379:methods*; D008856:Microscopy, Fluorescence / Q000379:methods; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D013183:Sputum / Q000382:microbiology*; D013997:Time Factors; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000382:microbiology
Magnetic beads; Mycobacterium tuberculosis; Smear microscopy; TB-Beads