TABLE 4.

An mtrR mutation is required for expression of penB-mediated penicillin and nafcillin resistancea

StrainmtrRpenMIC (μg/ml)
TETPENNAFTX-100
FA19+0.250.0150.25250
FA19AB+penA4, penB0.250.061.0250
WV38mtrR171penA4, penB1.00.58.0>16,000
  • 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).