Molecular Characterisation of Trimethoprim Resistance in Escherichia coli and Klebsiella pneumoniae during a 2 year intervention on Trimethoprim use
2010 (English)In: PLoS ONE, ISSN 1932-6203, Vol. 5, no 2, e9233- p.Article in journal (Refereed) Published
BACKGROUND: Trimethoprim resistance is increasing in Enterobacteriaceae. In 2004-2006 an intervention on trimethoprim use was conducted in Kronoberg County, Sweden, resulting in 85% reduction in trimethoprim prescriptions. We investigated the distribution of dihydrofolate reductase (dfr)-genes and integrons in Escherichia coli and Klebsiella pneumoniae and the effect of the intervention on this distribution. METHODOLOGY/PRINCIPAL FINDINGS: Consecutively isolated E. coli (n = 320) and K. pneumoniae (n = 54) isolates phenotypically resistant to trimethoprim were studied. All were investigated for the presence of dfrA1, dfrA5, dfrA7, dfrA8, dfrA12, dfrA14, dfrA17 and integrons class I and II. Isolates negative for the seven dfr-genes (n = 12) were also screened for dfr2d, dfrA3, dfrA9, dfrA10, dfrA24 and dfrA26. These genes accounted for 96% of trimethoprim resistance in E. coli and 69% in K. pneumoniae. The most prevalent was dfrA1 in both species. This was followed by dfrA17 in E. coli which was only found in one K. pneumoniae isolate. Class I and II Integrons were more common in E. coli (85%) than in K. pneumoniae (57%). The distribution of dfr-genes did not change during the course of the 2-year intervention. CONCLUSIONS/SIGNIFICANCE: The differences observed between the studied species in terms of dfr-gene and integron prevalence indicated a low rate of dfr-gene transfer between these two species and highlighted the possible role of narrow host range plasmids in the spread of trimethoprim resistance. The stability of dfr-genes, despite large changes in the selective pressure, indirectly suggests a low fitness cost of dfr-gene carriage.
Place, publisher, year, edition, pages
2010. Vol. 5, no 2, e9233- p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-112601DOI: 10.1371/journal.pone.0009233ISI: 000274590500015PubMedID: 20169085OAI: oai:DiVA.org:uu-112601DiVA: diva2:286937