TABLE 3.

MtrD mutations eliminate the contribution of mtr and penB, but not that of penA, to penicillin and nafcillin resistancea

StrainmtrRmtrDpenMIC (μg/ml)
TETERYPENNAFTX-100
FA19++0.250.250.0150.25250
WV30mtrR171+0.252.00.031.0>16,000
WV31mtrR171mtrD::kan0.250.060.0150.0315
WV32++penA40.250.250.1254.0250
WV33+mtrD::kanpenA40.250.060.1250.2515
WV34mtrR171+penA40.252.00.2516>16,000
WV35mtrR171mtrD::kanpenA40.250.060.1250.2515
WV36mtrR171+penA4, penB1.02.01.032>16,000
WV37mtrR171mtrD::kanpenA4, penB0.250.060.060.2531
  • a All abbreviations are as described in Table 2, footnote a. MICs are representative values from at least three determinations. +, wild type; −, no mutation in pen genes (see Table 1, footnote a).