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- Trobos, Margarita, 1980, et al.
(författare)
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Characterization of sulphonamide-resistant Escherichia coli using comparison of sul2 gene sequences and multilocus sequence typing.
- 2009
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Ingår i: Microbiology (Reading, England). - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 155:Pt 3, s. 831-836
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Trobos, Margarita, 1980, et al.
(författare)
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Natural transfer of sulphonamide and ampicillin resistance between Escherichia coli residing in the human intestine.
- 2009
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Ingår i: The Journal of antimicrobial chemotherapy. - : Oxford University Press (OUP). - 1460-2091 .- 0305-7453. ; 63:1, s. 80-6
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate whether the sulphonamide resistance gene sul2 could be transferred between Escherichia coli in the human gut.Nine volunteers ingested a 10(9) cfu suspension of sulphonamide-susceptible, rifampicin-resistant E. coli recipients of human origin. Three hours later, they ingested a 10(7) cfu suspension of a sulphonamide-resistant (MIC>1024 mg/L) E. coli donor of pig origin. Stool samples were collected 24 h prior to ingestion, daily for 7 days and at days 14 and 35. Samples were plated on selective plates and monitored for the acquisition of sulphonamide-resistance by the recipient from the indigenous or administrated donor E. coli. Possible transconjugants were typed by PFGE and tested for the presence of plasmids containing the sul2 gene, which was also sequenced.Concentrations of the human and animal E. coli reached a maximum of 7.5x10(6) cfu/g faeces and colonized for more than 7 days, and 2x10(8) cfu/g for more than 14 days, respectively. On day 2, a transconjugant was detected in one volunteer. This volunteer was colonized with sulphonamide-resistant E. coli at day 0. The transconjugant was sul2-positive, had an MIC>1024 mg/L for sulfamethoxazole and the same PFGE profile as the recipient. The resident E. coli transferred a plasmid (>63 kb), containing the sul2 gene, to the recipient. The sul2 sequence of the transconjugant was identical to that of the volunteer's own E. coli from day 0, but differed from the animal strain. Co-transfer of ampicillin resistance was also demonstrated.Transfer of sul2 was observed between E. coli bacteria in the human intestine. The transconjugant's sul2 gene came from the volunteer's own flora. The origin of the E. coli donor is unknown.
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