Journal
ANTIMICROBIAL AGENTS AND CHEMOTHERAPY
Volume 53, Issue 3, Pages 1177-1184Publisher
AMER SOC MICROBIOLOGY
DOI: 10.1128/AAC.00485-08
Keywords
-
Categories
Funding
- Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC)
- Merck Sharp and Dohme, Spain
- Spanish Network for Research in Infectious Diseases (REIPI) [RD06/0008/0025]
- Conseller a de Sanidad, SERGAS [PS07/90]
- Fondo de Investigaciones Sanitarias [PI061368, PI081613]
Ask authors/readers for more resources
As a part of a nationwide study in Spain, 15 clinical isolates of Acinetobacter genomic species 3 (AG3) were analyzed. The main objective of the study was to characterize the ampC genes from these isolates and to determine their involvement in beta-lactam resistance in AG3. The 15 AG3 isolates showed different profiles of resistance to ampicillin (range of MICs, 12 to > 256 mu g/ml). Nucleotide sequencing of the 15 ampC genes yielded 12 new AmpC enzymes (ADC-12 to ADC-23). The 12 AG3 enzymes showed 93.7 to 96.1% amino acid identity with respect to the AmpC enzyme from Acinetobacter baumannii (ADC-1 enzyme). Eight out of fifteen ampC genes were expressed in Escherichia coli cells under the control of a common promoter, and with the exception of one isolate (isolate 65, which showed lower beta-lactam MICs), significant differences in overall beta-lactam MICs for E. coli cells expressing AG3 ampC genes were not revealed. No significant differences in ampC gene expression in AG3 clinical isolates were revealed by reverse transcription-PCR analysis. A detailed analysis of the 12 AmpC protein sequences revealed that amino acid replacements (in comparison with those of ADC-1) occurred mainly in the same positions, although none were located in important functional domains such as the Omega-loop or conserved beta-lactamase motifs. Kinetic experiments performed with three representative AmpC enzymes (ADC-14, -16, and -18) in some cases revealed dramatic changes in K-m and k(cat) values for beta-lactams. No ISAba1 was detected upstream of the ampC genes. Our results reveal 12 new ampC genes in AG3. The enzymes showed a moderate degree of variability, and they are tentatively named ADC-12 to ADC-23.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available