To determine the sensitivity of the multiplex PCR assay, 1 ml of
exponential phase cultures containing 1.4 108
CFU and
9.5 107
CFU for S. flexneri 2457T and 2457M, was used to extract
DNA by the 5-min boiling method. Aliquots of genomic DNA were
frozen for storage and serially diluted 10-fold with sterile water at
the time of the experiment. DNA templates of each bacterium
representing 105
,104
,103
,102
, 10 and 1 colony forming-unit (CFU)
were subjected to the multiplex PCR.