Open AccessMutations in the ampC promoter of Escherichia coli isolates resistant to oxyiminocephalosporins without extended spectrum β‐lactamase production
Author(s) -
Caroff N,
Espaze E,
Bérard I,
Richet H,
Reynaud A
Publication year - 1999
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1999.tb13539.x
Subject(s) - promoter , escherichia coli , attenuator (electronics) , biology , gene , mutation , genetics , microbiology and biotechnology , insertion sequence , mutant , gene expression , transposable element , physics , attenuation , optics
Escherichia coli strains showing an increased resistance to oxyiminocephalosporins without an extended spectrum β‐lactamase production have been screened for mutations in their ampC β‐lactamase gene promoter. Mutations were found by direct sequencing of seven promoters at positions −42, −32 (box −35), −18, −1, +5, +24 (attenuator), +31 (attenuator) and +58. By using rapid and simple methods, three of these mutations (−42, −32 and +24), which could enhance transcription, were searched in 37 resistant and 25 sensitive isolates. The −42 mutation was present in 33 of the 37 promoters from the resistant isolates. The −32 and +24 mutations were present only in three and two promoters, respectively, and they were combined in the most resistant strain of the study. The +24 mutation was detected in another strain associated with a 1‐bp insertion between the −35 and −10 conserved sequences. None of these mutations was detected in the ampC β‐lactamase from the sensitive isolates.