Fig. 1

Effect of fluorescent labeling on B. pertussis viability. a Conjugation of B. pertussis Tohama I with Alexa Fluor® 488 was performed as described in Materials and Methods. After washes, bacteria were suspended in PBS. Bacterial suspension was serially diluted and plated on BG agar plates immediately after labeling (blue), and 2 h (red) after incubation at 37 °C. Results represent mean ± SD from a representative experiment performed in triplicates. b Labeled bacteria were fixed (green) and stained with DAPI (blue) for confocal microscopy analysis