Experimental research on utilization of bioluminescent technique to substitute the current viability count for BCG...

The possibility of using the bioluminescent (BL) technique to substitute the traditional viability count of colony forming units (CFU) of BCG vaccine was investigated. The results showed there is a significant dose-dependent correlation between the concentration of standard adenosine triphosphate (ATP) and ATP BL value. The ultrasonic-chloroform method designed by us yielded the best results. The correlation coefficient values (r) of BL of the liquid and lyophilized vaccine were found to be 0.8 155 and 0.8 484 respectively (P less than 0.05). The coefficient of variation (CV) between the BL value of different lots of ATP obtained was 3.2-4.4%, much lower than that of CFU (CV = 10.4-11.2%). The presence of bacterial clumps within the vaccine had great influence on the bacterial ATP value and on the CFU viability count. 2.8 fg of ATP was found in each CFU formed in the vaccine with clumps, while it was only 0.94 fg in the vaccine without clumps, indicating the superiority of the BL method. The BL method has shown a high sensitivity, good reproducibility and simplicity in handling with quick results and high accuracy. Therefore, we consider that the BL method can be used to substitute the CFU method.