Table 2. Comparison of performance of different methods for assaying B. burgdorferi viability.
| MTT | XTT | FDA | LIVE/DEAD | LIVE/DEAD5 | Sytox/Hoechst | SYBR Green I/PI | Microscope counting6 | |
| Detection limit1 | >108 | ND4 | 107 | ND | 5×105 | ∼8×106 | 105 | 2.5×104 |
| Error2 | ND | ND | 30%∼40% | ND | 20%∼30% | 30% | <10% | 10%∼20% |
| Time3 | 3∼5 h | 2.5 h | 1 h | 20 min | 50 min | 2 h | 20 min | ∼48 h |
| Background signal | Low | Very strong | Near detection limit | Very strong | Low | Low | Low | No effect |
1
Number of cells per 100 µl culture. Linear regression analysis (least squares regression method) was used to determine the detection limit of the assays. No linear-relationship (r <0.9) between cell numbers and corresponding measurement value was observed when the cell number is less than the detection limit. The values for linear regression analysis are the mean of three replicates.
2
Percentage of relative error from three time measurements.
3
Test time required for completing a 96-well plate assay.
4
ND: Not determined, due to weak signal of cells and/or strong background signal from BSK-H medium.
5
BSK-H medium was removed by washing prior to LIVE/DEAD BacLight assay.
6
Samples were stained with LIVE/DEAD BacLight assay.