Article Figures & Data
Figures
- FIG. 1.
Biofilm formation by S. intermedius WT (continuous line), luxS mutant SI006 (dotted line), and luxS mutant SI006 supplemented with 0.8 nM DPD (interrupted line) following 12 h of incubation in the presence of sub-MICs of ampicillin (A), ciprofloxacin (B), and tetracycline (C). The data points represent mean values (n = 9) with the standard errors of the means. *, significant increase (P ≤ 0.05) in biofilm formation by S. intermedius WT (continuous line) but not luxS mutant SI006 (dotted line); OD530, optical density at 530 nm.
- FIG. 2.
Scanning electron microscopy images of biofilms of the S. intermedius WT (A), luxS mutant SI006 (B), and luxS mutant SI006 supplemented with 0.8 nM DPD (C) following 12 h of incubation in the absence of antibiotics (control) (panels 1) and in the presence of 0.04 μg/ml ampicillin (panels 2), 0.15 μg/ml ciprofloxacin (panels 3), or 0.08 μg/ml tetracycline (panels 4).
- FIG. 3.
Luminescence (ATP level) as a measure of metabolic activity in planktonic cell cultures determined by the BacTiter-Glo viability assay following 12 h of incubation of the S. intermedius WT (continuous line), luxS mutant SI006 (dotted line), and luxS mutant SI006 supplemented with 0.8 nM AI-2 (interrupted line) in the presence of sub-MICs of ampicillin (A), ciprofloxacin (B), and tetracycline (C). The data points represent mean values (n = 12) with the standard errors of the means. *, significantly higher (P ≤ 0.05) ATP levels in the S. intermedius WT (continuous line) than in the luxS mutant SI006 (dotted line).
Tables
- TABLE 1.
Biofilm CFU of S. intermedius WT, luxS mutant SI006, and DPD-supplemented luxS mutant SI006 cultured in medium with or without antibiotics at sub-MICs
Drug and concn (μg/ml) CFU (105/ml)a WT SI006 SI006 + DPD 0.00 (control) 402.9 (26.88) 310.8 (17.10) 413.7 (24.47) Ampicillin 0.02 486.2 (64.04) 324.1 (25.43) 459.5 (29.33) 0.04 621.6 (64.77) 268.6 (28.65) 686.0 (65.32) 0.06 894.7 (182.65) 162.1 (36.63) 819.2 (43.61) Ciprofloxacin 0.10 768.1 (42.63) 324.1 (24.96) 814.7 (47.58) 0.15 663.8 (36.30) 333.0 (25.04) 768.1 (44.00) 0.20 577.2 (32.39) 131.0 (19.28) 519.5 (36.40) Tetracycline 0.05 779.2 (61.02) 333.0 (16.49) 828.1 (25.83) 0.07 637.1 (66.99) 253.1 (17.20) 708.2 (53.33) 0.10 610.5 (76.86) 108.8 (37.27) 486.2 (48.24) ↵a Data are for six isolates of each strain and condition. Values in parentheses are standard errors of the means.
- TABLE 2.
CFU in planktonic cultures of S. intermedius WT, luxS mutant SI006, and DPD-supplemented luxS mutant SI006 cultured with or without antibiotics at sub-MICs
Drug and concn (μg/ml) CFU (108/ml)a WT SI006 SI006 + DPD Ampicillin 0.00 (control) 771.7 (35.14) 798.3 (37.09) 793.3 (42.40) 0.06 61.2 (4.01) 41.8 (3.43) 48.7 (55.06) 0.08 43.3 (3.45) 16.4 (1.7) 39.1 (6.31) 0.10 45.3 (6.72) 10.3 (4.22) 39.6 (6.31) 0.12 20.7 (1.79) 8.5 (1.39) 18.4 (2.48) Ciprofloxacin 0.00 (control) 756.9 (62.98) 708.1 (47.64) 768.6 (46.24) 0.20 5.87 (0.52) 2.60 (0.51) 5.30 (0.21) 0.25 5.14 (0.77) 1.16 (0.26) 4.72 (0.67) 0.30 3.12 (0.38) 0.74 (0.17) 3.1 (0.37) 0.35 2.6 (0.34) 0.4 (0.13) 2.3 (0.18) Tetracycline 0.00 (control) 791.7 (44.10) 757.5 (80.14) 790.8 (90.09) 0.08 61.9 (6.58) 11.2 (2.88) 38.4 (4.87) 0.10 44.5 (8.52) 5.7 (1.16) 25.2 (2.72) 0.12 32.0 (5.92) 3.0 (0.94) 16.3 (1.86) 0.15 24.2 (5.23) 2.0 (0.73) 10.1 (1.75) ↵a Data are for six isolates of each strain and condition. Values in parentheses are standard errors of the means.
