Table 3.

MICs of β-lactam antibiotics and specific activities ofE. cloacae AmpC in E. coli ampD mutants containing the ampDE genes ofP. aeruginosa mutant

Strain and plasmidsRelevant genotypeMIC (μg/ml)β-Lactamase activitya
AmpicillinCefotaximeNoninducedInducedb
STC172/pEC1C/pBGS19+c ampC+ampR+/ampD11E+ 1,024323,260 ± 19023,490 ± 1,240
STC172/pEC1C/pHUL4DE-2c ampC+ampR+/ampDEPAO11281113 ± 52,930 ± 199
STC172/pEC1C/pHUL4DE-M1 ampC+ampR+/ampDE4254128<232 ± 12,000 ± 60
STC172/pEC1C/pHUL4DE-M2 ampC+ampR+/ampDEPs50SAI+ 128<230 ± 1200 ± 10
STC172/pEC1C/pHUL4DE-M3 ampC+ampR+/ampDEPs50SAI−con 512<220 ± 1900 ± 4
STC172/pEC1C/pHUL4DE-M4 ampC+ampR+/ampDEM1405256<2400 ± 20800 ± 40
STC172/pEC1C/pHUL4DE-M5 ampC+ampR+/ampDEM2297P256<220 ± 0.7832 ± 50
STC172/pEC1C/pHUL4DE-M6 ampC+ampR+/ampDEM2297P−con 256<2134 ± 62,100 ± 90
JRG582/pEC1C/pBGS19+c ampC+ampR +/Δ(ampDE)21,02464103,280 ± 6,230109,400 ± 7,110
JRG582/pEC1C/pHUL4DE-2c ampC+ampR+/ampDEPAO11288414 ± 397,050 ± 400
JRG582/pEC1C/pHUL4DE-M5 ampC+ampR+/ampDEM2297P256<260 ± 41,130 ± 70
JRG582/pEC1C/pHUL4DE-M6 ampC+ampR+/ampDEM2297P−con 256<2105 ± 81,770 ± 80
  • a Nanomoles of nitrocefin hydrolyzed per minute per milligram of protein.

  • b Induction was carried out with 4 μg of cefoxitin/ml for 1 h.

  • c Data from Langaee et al. (19).