Fig. 2.

Susceptibility of log phase (5 days) and stationary phase (8 days) Borrelia burgdorferi to antimicrobial agents after a three-day treatment determined by (A) SYBR Green I/PI assay, (B) direct counting of live and dead cells stained using a mixture of SYBR Green I and propidium iodide using fluorescent microscopy. (C) Representative live/dead images of log and stationary phase B. burgdorferi to antimicrobial agents taken at 200× magnification (Scale bar – 100 μm). Doxycycline (DoxC) was used as a positive control. 1× PBS and 25% alcohol were used as negative controls, respectively. All antibiotics individually as well as in combination were used at a concentration of 10 μg/ml. Stevia A was used at a concentration of 1.2 μg/ml. n = 3 ± SD, ^*p ≤ 0.05, ^**p ≤ 0.01 compared to the control. n = 3 ± SD, ⁺p ≤ 0.05, ⁺⁺p ≤ 0.01 (doxycycline compared to Stevia A). n = 3 ± SD, ^*p ≤ 0.05, ^**p ≤ 0.01 (doxycycline compared to Stevia A). Abbreviations: doxycycline – DoxC, cefoperazone – CefP, daptomycin – DapM