First detection of the staphylococcal trimethoprim resistance gene dfrK and the dfrK-carrying transposon Tn559 in enterococci

  1. López, M. 1
  2. Kadlec, K. 2
  3. Schwarz, S. 2
  4. Torres, C. 1
  1. 1 Universidad de La Rioja

    Universidad de La Rioja

    Logroño, España

    GRID grid.119021.a

  2. 2 Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut (FLI), Neustadt-Mariensee, Germany
Microbial Drug Resistance

ISSN: 1076-6294

Year of publication: 2012

Volume: 18

Issue: 1

Pages: 13-18

Type: Article

Export: RIS
DOI: 10.1089/mdr.2011.0073 SCOPUS: 2-s2.0-84856715720 WoS: 000300041300003 GOOGLE SCHOLAR


Cited by

  • Scopus Cited by: 26 (12-06-2021)

Journal Citation Reports

  • Year 2012
  • Journal Impact Factor: 2.364
  • Best Quartile: Q2
  • Area: PHARMACOLOGY & PHARMACY Quartile: Q2 Rank in area: 117/261 (Ranking edition: SCIE)
  • Area: MICROBIOLOGY Quartile: Q3 Rank in area: 59/116 (Ranking edition: SCIE)
  • Area: INFECTIOUS DISEASES Quartile: Q3 Rank in area: 39/70 (Ranking edition: SCIE)

SCImago Journal Rank

  • Year 2012
  • SJR Journal Impact: 0.963
  • Best Quartile: Q1
  • Area: Medicine (miscellaneous) Quartile: Q1 Rank in area: 587/2943
  • Area: Immunology Quartile: Q2 Rank in area: 94/210
  • Area: Microbiology (medical) Quartile: Q2 Rank in area: 37/120
  • Area: Microbiology Quartile: Q2 Rank in area: 60/146
  • Area: Pharmacology Quartile: Q2 Rank in area: 102/360


  • Year 2012
  • CiteScore: 3.3
  • Area: Microbiology (medical) Percentile: 59
  • Area: Pharmacology Percentile: 53
  • Area: Microbiology Percentile: 53
  • Area: Immunology Percentile: 40


The trimethoprim resistance gene dfrK has been recently described in Staphylococcus aureus, but so far has not been found in other bacteria. A total of 166 enterococci of different species (E. faecium, E. faecalis, E. hirae, E. durans, E. gallinarum, and E. casseliflavus) and origins (food, clinical diseases in humans, healthy humans or animals, and sewage) were studied for their susceptibility to trimethoprim as determined by agar dilution (European Committee on Antimicrobial Susceptibility Testing) and the presence of (a) the dfrK gene and its genetic environment and (b) other dfr genes. The dfrK gene was detected in 49% of the enterococci (64% and 42% of isolates with minimum inhibitory concentrations of ≥2mg/L or ≤1mg/L, respectively). The tet(L)-dfrK linkage was detected in 21% of dfrK-positive enterococci. The chromosomal location of the dfrK gene was identified in one E. faecium isolate in which the dfrK was not linked to tet(L) gene but was part of a Tn559 element, which was integrated in the chromosomal radC gene. This Tn559 element was also found in 14 additional isolates. All combinations of dfr genes were detected among the isolates tested (dfrK, dfrG, dfrF, dfrK+dfrG, dfrK+dfrF, dfrF+dfrG, and dfrF+dfrG+dfrK). The gene dfrK gene was found together with other dfr genes in 58% of the tested enterococci. This study suggested an exchange of the trimethoprim resistance gene dfrK between enterococci and staphylococci, as previously observed for the trimethoprim resistance gene dfrG. © Copyright 2012, Mary Ann Liebert, Inc. 2012.