Table 3 

Discrepant TBbead FM results compared with culture: results of direct ZN and concentrated FM, and blinded rechecking of Magnetic bead results 

Lab No 
Direct ZN 
Conc FM 
Magnetic beadFM 
Magnetic bead reread* 


Magnetic bead false positives (compared to culture) 



261 
Negative 
Negative 
3+ 
3+ 


206 
Negative 
Negative 
1 AFB/40F 
Negative 


099 
Negative 
Negative 
1 AFB/40F 
Negative 


259 
Negative 
Negative 
3+ 
3+ 


296 
Negative 
Negative 
8 AFB/40F 
Negative 


082 
Negative 
1+ 
13 AFB/40F 
Negative 


276 
Negative 
Negative 
2 AFB/40F 
Negative 


203 
Negative 
Negative 
1 AFB/40F 
Negative 


287 
Negative 
Negative 
1 AFB/40F 
Negative 


262 
Negative 
Negative 
1 AFB/40F 
3+ 


141 
Negative 
Negative 
1 AFB/40F 
2 AFB/40F 


256 
Negative 
Negative 
2 AFB/40F 
13 AFB/40F 


096 
Negative 
Negative 
1 AFB/40F 
8 AFB/40F 


180 
Negative 
Negative 
3 AFB/40F 
1 AFB/40F 


131 
Negative 
Negative 
1 AFB/40F 
1 AFB/40F 


299 
Negative 
Negative 
3+ 
1+ 


302 
Negative 
Negative 
2 AFB/40F 
3+ 


211 
Negative 
1+ 
4 AFB/40F 
Negative 


267 
Negative 
Negative 
2 AFB/40F 
3 AFB/40F 


299 
Negative 
Negative 
2 AFB/40F 
1+ 


Magnetic bead false negatives compared to culture (with one or more positive result by conc FM or ZN)** 



283 
5 AFB/40F 
2+ 
Negative 
1+ 


280 
2 AFB/40F 
2+ 
Negative 
2 AFB/40F 


260 
1+ 
2+ 
Negative 
1+ 


258 
6 AFB/40F 
3+ 
Negative 
Negative 


151 
1+ 
3+ 
Negative 
Negative 


084 
1+ 
1+ 
Negative 
Negative 


294 
Negative 
15 AFB/40F 
Negative 
Negative 


292 
Negative 
5 AFB/40F 
Negative 
3 AFB/40F 


210 
Negative 
2 AFB/40F 
Negative 
Negative 


157 
Negative 
8 AFB/40F 
Negative 
Negative 


034 
Negative 
5 AFB/40F 
Negative 
Negative 


053 
Negative 
1+ 
Negative 
Negative 


050 
Negative 
3+ 
Negative 
3 AFB/40F 


011 
3 AFB/40F 
Negative 
Negative 
4 AFB/40F 


* Slides were blindly rechecked **An additional 23 specimens had false negative results by all three microscopy methods and rechecking was not performed. 

Albert et al. BMC Infectious Diseases 2011 11:125 doi:10.1186/1471233411125 