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High-level amikacin resistance in Pseudomonas aeruginosa associated with a 3'-phosphotransferase with high affinity for amikacin |
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| Authors: | Torres C Perlin M H Baquero F Lerner D L Lerner S A |
| Affiliation: | a Department of Biochemistry and Molecular Biology, University of La Rioja, Avenida de la Paz 105, 26004, Logroño, Spain b Department of Biology, University of Louisville, Louisville, KY 40292, USA c Microbiology Laboratory, Hospital Ramón y Cajal, 28034, Madrid, Spain d Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110, USA e Departments of Medicine and Biochemistry, Wayne State University, Detroit, MI 48201, USA |
| Abstract: | This work describes the characterization of the phosphotransferase enzymatic activity responsible for amikacin resistance in two clinical Pseudomona aeruginosa strains, isolated from a hospital that used amikacin as first-line aminoglycoside. Amikacin-resistant P. aeruginosa PA40 and PA43 (MIC: 128 mg/l) were shown to have APH activity with a substrate profile similar to that of APH(3′)-VI. The enzyme from P. aeruginosa PA40 was purified to >70% homogeneity. The Km of amikacin for this enzyme was 1.4 μM, the Vmax/Km ratio for amikacin was higher than for the other aminoglycosides tested and PCR and DNA sequencing ruled out the presence of aph(3′)-IIps. Amikacin resistance in this strain was, therefore, associated with APH(3′)-VI and the high affinity of this enzyme for amikacin could explain the high-level resistance that we observed. |
| Keywords: | Pseudomonas aeruginosa Amikacin resistance APH(3′)-VI Purification Kinetics analyses |
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