Artículo
Genetic Variability among ampC Genes from Acinetobacter Genomic Species 3
Autor/es | Beceiro Casas, Alejandro
Pérez, Astrid Fernández-Cuenca, Felipe Martínez-Martínez, Luis Pascual Hernández, Álvaro ![]() ![]() ![]() ![]() ![]() ![]() ![]() Vila, Jordi Rodríguez-Baño, Jesús ![]() ![]() ![]() ![]() ![]() ![]() ![]() Cisneros, José Miguel ![]() ![]() ![]() ![]() ![]() ![]() ![]() Pachón Díaz, Jerónimo ![]() ![]() ![]() ![]() ![]() ![]() ![]() Bou, Germán |
Departamento | Universidad de Sevilla. Departamento de Medicina |
Fecha de publicación | 2009-03 |
Fecha de depósito | 2016-05-13 |
Publicado en |
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Resumen | 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 ... 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 B-lactam resistance in AG3. The 15 AG3 isolates showed different profiles of resistance to ampicillin (range of MICs, 12 to >256 μg/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 B-lactam MICs), significant differences in overall B-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 Ω- loop or conserved B-lactamase motifs. Kinetic experiments performed with three representative AmpC enzymes (ADC-14, -16, and -18) in some cases revealed dramatic changes in Km and kcat values for B-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 |
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