Séverine Bontron1, Laurent Poirel1,2,3, Nicolas Kieffer1,2,3, Encho Savov4, Angelina Trifonova4, Iva Todorova4, Gwendoline Kueffer1, Patrice Nordmann1,2,3,5. 1. 1 Medical and Molecular Microbiology Unit, Department of Medicine, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland. 2. 2 INSERM European Unit (IAME, France), University of Fribourg, Fribourg, Switzerland. 3. 3 Swiss National Reference Center for Emerging Antibiotic Resistance (NARA), University of Fribourg, Fribourg, Switzerland. 4. 4 Military Medical Academy, Sofia, Bulgaria. 5. 5 Institute for Microbiology, University of Lausanne and University Hospital Centre, Lausanne, Switzerland.
Abstract
Objective: The aim of the study was to decipher the mechanisms and associated genetic determinants responsible for increased carbapenem resistance among Proteus mirabilis clinical isolates. Methods: The entire genetic structure surrounding the β-lactam resistance genes was characterized by PCR, gene walking, and DNA sequencing. Results: A series of clinical P. mirabilis isolates were consecutively recovered from different patients at the Military hospital of Sofia, Bulgaria. They showed variable levels of resistance to carbapenems. All isolates produced the same carbapenemase VIM-1 that was chromosomally encoded. We showed that increased resistance to carbapenems was related to an increased number of blaVIM-1 gene copies. Conclusion: We showed here that increased carbapenem resistance in P. mirabilis may result from increased expression of the blaVIM-1 carbapenemase gene through multiplication of its copy number.
Objective: The aim of the study was to decipher the mechanisms and associated genetic determinants responsible for increased carbapenem resistance among Proteus mirabilis clinical isolates. Methods: The entire genetic structure surrounding the β-lactam resistance genes was characterized by PCR, gene walking, and DNA sequencing. Results: A series of clinical P. mirabilis isolates were consecutively recovered from different patients at the Military hospital of Sofia, Bulgaria. They showed variable levels of resistance to carbapenems. All isolates produced the same carbapenemase VIM-1 that was chromosomally encoded. We showed that increased resistance to carbapenems was related to an increased number of blaVIM-1 gene copies. Conclusion: We showed here that increased carbapenem resistance in P. mirabilis may result from increased expression of the blaVIM-1 carbapenemase gene through multiplication of its copy number.