TABLE 6.

MICs of antibiotics for S. mutans strains

AntibioticMICa
XcXc106Xc41Xc146
Kanamycin60 ± 0d53.3 ± 9.4e20 ± 0b,g16.7 ± 4.7b,f
Spectinomycin100 ± 0d93.3 ± 9.480 ± 0b73.3 ± 9.4c,h
Bacitracin4.0 ± 0.0d,f0.033 ± 0.009b,d0.73 ± 0.09b,f0.02 ± 0.00b,d
Ampicillin0.06 ± 0.00d0.06 ± 0.00d0.04 ± 0.00b,f0.04 ± 0.00b,f
Nisin100 ± 0d100 ± 0d0.25 ± 0.00b,f0.23 ± 0.02b,f
  • a Results are expressed in micrograms per milliliter, except for those with bacitracin, which are in international units per milliliter. Each value represents the mean ± standard deviation for assays performed three times.

  • b Differences from strain Xc (P < 0.01 [Welch's t test]).

  • c Differences from strain Xc (P < 0.05 [Welch's t test]).

  • d Differences from strain Xc41 (P < 0.01 [Welch's t test]).

  • e Differences from strain Xc41 (P < 0.05 [Welch's t test]).

  • f Differences from strain Xc106 (P < 0.01 [Welch's t test]).

  • g Differences from strain Xc106 (P < 0.05 [Welch's t test]).

  • h Differences from strain Xc106 (P < 0.1 [Welch's t test]).