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

StrainmtrRmtrDpenMIC (μg/ml)
WV30 mtrR171 +>16,000
WV31 mtrR171 mtrD::kan0.250.060.0150.0315
WV32++ penA4
WV33+ mtrD::kan penA4
WV34 mtrR171 + penA4>16,000
WV35 mtrR171 mtrD::kan penA4
WV36 mtrR171 + penA4, penB>16,000
WV37 mtrR171 mtrD::kan penA4, penB
  • 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).