TABLE 3.

MICs of β-lactam and tetracycline antibiotics for strains containing wild-type (WT) or variant PIBs

AntibioticMIC for the following PIBs in FA19 penA4 mtrRa
WTG120D/ A121DG120P/ A121PG120R/ A121HG120K
Cefotaxime0.014b0.0270.0240.0360.036
Cefmetazole3.08.46.09.612.0
Cefoxitin0.751.51.52.11.8
Penicillin0.320.670.580.750.75
Tetracycline0.451.01.51.51.5
Oxytetracycline0.51.01.01.02.0
Chlortetracycline1.02.02.02.02.0
Doxycycline0.671.01.01.01.0
  • a The identity of the porin in strain FA19 penA mtrR is shown. Strains were constructed by transformation with wild-type or altered porB DNA constructs as described in Materials and Methods.

  • b MICs (in micrograms/milliliter) were determined as described previously (28). MICs are the averages of three independent experiments.