TABLE 2.

Insertional inactivation of MtrD eliminates the intermediate- and high-level chromosomally mediated penicillin resistance of strains FA140 and FA6140a

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
FA140mtrR140+penA2, penB21.02.01.08.0>16,000
WV24mtrR140mtrD::kanpenA2, penB20.250.060.060.12531
FA6140mtrR171+penA4, penB, ponA14.02.04.032>16,000
WV22mtrR171mtrD::kanpenA4, penB, ponA11.00.060.251.031
  • a MIC of TET (tetracycline), ERY (erythromycin), PEN (penicillin G), NAF (nafcillin), and TX-100 are representative values for three or more determinations. +, wild type; −, no mutation in pen genes (see Table 1, foonote a).