Cephalosporinase over-expression resulting from insertion of ISAba1 in Acinetobacter baumannii

Clin Microbiol Infect. 2006 Feb;12(2):123-30. doi: 10.1111/j.1469-0691.2005.01320.x.


ISAba1-like sequences were identified immediately upstream of the bla(ampC) gene in ceftazidime-resistant Acinetobacter baumannii isolates, but were absent in ceftazidime-susceptible A. baumannii isolates. AmpC over-expression resulted from insertion of ISAba1-like sequences upstream of bla(ampC). ISAba1 provided strong promoter sequences, and it was demonstrated that the change in the ribosome binding site sequence resulting from insertion of ISAba1 did not influence expression of the bla(ampC) gene. Sequence analysis revealed that AmpC sequences of A. baumannii isolates were almost identical and that ISAba1 elements had a high percentage of identity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter baumannii / enzymology
  • Acinetobacter baumannii / genetics*
  • Amino Acid Sequence
  • Bacterial Proteins / biosynthesis
  • Bacterial Proteins / genetics
  • Base Sequence
  • Cephalosporinase / biosynthesis*
  • Cephalosporinase / genetics
  • DNA Transposable Elements / genetics*
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • Gene Expression
  • Microbial Sensitivity Tests
  • Molecular Sequence Data
  • Promoter Regions, Genetic
  • Protein Biosynthesis
  • RNA, Messenger / genetics
  • Recombination, Genetic
  • Regulatory Sequences, Nucleic Acid / genetics
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • beta-Lactam Resistance / genetics*
  • beta-Lactamases / genetics


  • Bacterial Proteins
  • DNA Transposable Elements
  • DNA, Bacterial
  • RNA, Messenger
  • Cephalosporinase
  • AmpC beta-lactamases
  • beta-Lactamases