Molecular analysis of the carbapenem and metronidazole resistance mechanisms of Bacteroides strains reported in a Europe-wide antibiotic resistance survey

: Soki J, Eitel Z, Urban E, Nagy E, on behalf of the ESCMID Study Group on Anaerobic Infections (incl. Könönen E)

Publisher: ELSEVIER SCIENCE BV

: 2013

: International Journal of Antimicrobial Agents

: INTERNATIONAL JOURNAL OF ANTIMICROBIAL AGENTS

: INT J ANTIMICROB AG

: 2

: 41

: 2

: 122

: 125

: 4

: 0924-8579

DOI: https://doi.org/10.1016/j.ijantimicag.2012.10.001

Here we examine the carbapenem and metronidazole resistance mechanisms of 640 Bacteroides strains reported in the 2008-2009 European antibiotic susceptibility survey. Of the 22 strains with elevated imipenem minimum inhibitory concentrations (>4 mu g/mL), 10 were cfiA-positive and out of these 5 carried activating insertion sequence (IS) elements in the upstream regions of the cfiA genes. However, resistant strains with cfiA genes but with no activating IS elements were found (n = 2) as well as a resistant strain with no cfiA gene. In the former the resistance phenotypes by Etest were heterogeneous, whilst in the latter no carbapenemase production was seen; both mechanisms have been rarely observed, examined and characterised. Interestingly, few (n = 3) nim-positive strains were found, including one metronidazole-resistant strain harbouring nimE activated by ISBf6, and two susceptible strains harbouring chromosomally located nim genes. (C) 2012 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.