JAC Advance Access originally published online on May 8, 2009
Journal of Antimicrobial Chemotherapy 2009 64(1):163-168; doi:10.1093/jac/dkp156
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Original research |
Escherichia coli phylogenetic groups are associated with site of infection and level of antibiotic resistance in community-acquired bacteraemia: a 10 year population-based study in Denmark
1 Department of Clinical Microbiology, Aalborg Hospital, Aarhus University Hospital, Hobrovej 18-22, DK-9000 Aalborg, Denmark 2 Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Sohngaardsholmsvej 57, DK-9000 Aalborg, Denmark 3 Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 3, DK-9220 Aalborg Ø, Denmark 4 Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Allé 43, DK-8200 Aarhus N, Denmark
Received 26 January 2009; returned 3 March 2009; revised 6 April 2009; accepted 7 April 2009
* Corresponding author. Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Sohngaardsholmsvej 57, DK-9000 Aalborg, Denmark. Tel: +4599408520; Fax: +4596350558; E-mail: asb{at}bio.aau.dk
Objectives: The aim of this study was to assess whether Escherichia coli phylogenetic groups were associated with the site of infection and the level of antibiotic resistance in community-acquired bacteraemia (CAB).
Methods: The population-based cohort study included 1533 unique isolates of E. coli from Danish patients with CAB during a 10 year period. Triplex PCR was used to classify the phylogenetic groups, and susceptibility testing was performed by disc diffusion. Data were analysed using contingency tables and logistic regression.
Results: Overall, 65.9% of the 1533 E. coli isolates belonged to phylogroup B2, 16.6% to D, 13.1% to A and 4.4% to B1. B2 was the most prevalent group for all sites of infection, ranging from 69.9% in cases with a urinary tract site of infection to 54.8% in cases with a hepatobiliary tract site of infection. Antibiotic resistance to one and more than three antibiotics, respectively, was most frequent in group D (11.4%/33.9%), followed by A (5.5%/26.9%), B1 (5.9%/19.1%) and B2 (6.7%/7.5%). Regression analysis, with group B2 as reference, confirmed that groups A and B1 were associated with a site of infection other than the urinary tract and that groups A and D were associated with resistance to antibiotics including ampicillin, sulphonamide, trimethoprim, gentamicin and quinolones.
Conclusions: Phylogenetic group B2 was predominant in E. coli CAB. This was the least resistant of the four groups. Phylogroups A and B1 were associated with sites of infection other than the urinary tract, and resistance to multiple antibiotics was most prevalent for groups A and D.
Keywords: epidemiology , bloodstream infections , antimicrobials, PCR