Characterization of sulphonamide-resistant Escherichia coli using comparison of sul2 gene sequences and multilocus sequence typing.
The sul2 gene encodes sulphonamide resistance (Sul(R)) and is commonly found in Escherichia coli from different hosts. We typed E. coli isolates by multilocus sequence typing (MLST) and compared the results to sequence variation of sul2, in order to investigate the relation to host origin of pathogenic and commensal E. coli strains and to investigate whether transfer of sul2 into different genomic lineages has happened multiple times. Sixty-eight E. coli isolated in Denmark and Norway from different hosts and years were MLST typed and sul2 PCR products were sequenced and compared. PFGE was performed in a subset of isolates. All isolates were divided into 45 different sequence types (STs), with clonal complexes CC10, CC23, CC168, CC350 and CC69 being the most frequent. The sul2 gene from the majority of E. coli strains had only two point mutations, at positions 159 and 197, leading to a synonymous and a non-synonymous change, respectively. Five strains had extra single mutations. All poultry, poultry meat, and Danish human blood isolates had the same sul2 ST and some of these strains clustered under the same MLST STs, indicating that they shared habitats. Most PFGE profiles clustered according to source, but some included different sources. Sul(R) E. coli from different animals, food, human faeces and infections did not cluster according to their origin, suggesting that these habitats share E. coli and sul2 gene types. However, while pig isolates on one occasion clustered with urinary tract infection isolates, poultry isolates seemed more related to isolates from bloodstream infections in humans. Presence of mainly two types of the sul2 gene in both human and animal isolates, irrespective of date and geography, and the presence of both types in the same clonal lineages, suggest horizontal transfer of sul2.
Trobos
Margarita
M
National Center for Antimicrobials and Infection Control, Statens Serum Institut, Artillerivej 5, 2300 Copenhagen, Denmark.|Department of Disease Biology, Faculty of Life Sciences, University of Copenhagen, Grønnegårdsvej 15 st., 1870 Frederiksberg, Denmark.
Christensen
Henrik
H
Department of Disease Biology, Faculty of Life Sciences, University of Copenhagen, Grønnegårdsvej 15 st., 1870 Frederiksberg, Denmark.
Sunde
Marianne
M
National Veterinary Institute, Section of Bacteriology, Pb 750 Sentrum, 0106 Oslo, Norway.
Nordentoft
Steen
S
National Veterinary Institute, Technical University of Denmark, Section for Poultry, Hangovej 2, 8200 Aarhus, Denmark.
Agersø
Yvonne
Y
National Food Institute, Technical University of Denmark, Bülowsvej 27, 1790 Copenhagen, Denmark.
Simonsen
Gunnar S
GS
Department of Microbiology and Virology, Faculty of Medicine, University of Tromsø, Breivika, 9038 Tromsø, Norway.|Department of Microbiology and Infection Control, University Hospital of North Norway, Breivika, 9038 Tromsø, Norway.
Hammerum
Anette M
AM
National Center for Antimicrobials and Infection Control, Statens Serum Institut, Artillerivej 5, 2300 Copenhagen, Denmark.
Olsen
John E
JE
Department of Disease Biology, Faculty of Life Sciences, University of Copenhagen, Grønnegårdsvej 15 st., 1870 Frederiksberg, Denmark.
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D015373:Bacterial Typing Techniques; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D003718:Denmark; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D029968:Escherichia coli Proteins / Q000235:genetics*; D005243:Feces / Q000382:microbiology; D005516:Food Microbiology; D022761:Gene Transfer, Horizontal; D006801:Humans; D008460:Meat / Q000382:microbiology; D008969:Molecular Sequence Data; D009664:Norway; D017354:Point Mutation; D011200:Poultry / Q000382:microbiology; D017422:Sequence Analysis, DNA; D013552:Swine / Q000382:microbiology
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C491369:Sul2 protein, bacteria