5.Detection limit for multiplex PCR approach
The detection limit is evaluated by determining the numbers
of bacteria in a multiplex PCR system with a serial dilution.
(a)The bacterial suspension of 0.5 McFarland standard (ca.
1.5 × 108 CFU/mL) is diluted in a tenfold serial dilution
and an aliquot of each dilution inoculated on an agar plate
to determine the original number of bacteria in the suspension (CFU/mL).
(b)An aliquot of each dilution is heated at 100 °C for 15 min
and then centrifuged at 10,000 ×g for 1 min. The supernatant is then used as DNA template in the PCR.
The detection limit forN. gonorrhoeae isolates is defined
by the minimum concentration of bacteria (CFU/PCR
reaction) that can be amplified and detected on the 1.5 %
agarose gel.