Figure 3.

Growth of ATCC 49226 as measured via direct-qPCR and OD. One-hundred-thousand N. gonorrhoeae cells were inoculated into 10 mL of GW medium with (black points) and without (red points) 0.06 μL/mL of ciprofloxacin. Samples (300 μL) were taken every hour to perform the tests. All Cq values measured were normalized by subtracting each measured value with Cq at 0 h. (A) Direct-qPCR method exhibits higher quantification range and it differentiates the growth of drug-treated and nontreated cells in 1 h cultivation. (B) OD method shows a comparatively limited quantification capability with a narrower dynamic range. It differentiates the growth of drug-treated and nontreated cells in 9 h cultivation. As a point of comparison, 24-h incubation is the typical time frame cited for plate-based cultivation.¹¹