Molecular Characterisation of Trimethoprim Resistance in Escherichia coli and Klebsiella pneumoniae during a Two Year Intervention on Trimethoprim Use

PLoS One

Malin Grape¹  Martin Sundqvist¹  Alma Brolund²  Gunnar Kahlmeter³ 

[1] Department of Clinical Microbiology, Central Hospital, Växjö, Sweden;Department of Microbiology, Tumor and Cell Biology (MTC), Division of Clinical Microbiology, Karolinska Institutet, Stockholm, Sweden;Division of Infectious Diseases, Department of Medical Sciences, Uppsala University, Uppsala, Sweden

关键词: Klebsiella pneumoniae;    Trimethoprim resistance;    Antibiotic resistance;    Polymerase chain reaction;    Antibiotics;    Sequence analysis;    Escherichia coli;    Sweden;   

DOI  :  10.1371/journal.pone.0009233

学科分类：医学（综合）

来源: Public Library of Science

【 摘 要 】

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 phenotypicaly 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.

【 授权许可】

CC BY