Molecular Analysis of Tn 1546 in Enterococcus faecium Isolated from Animals and Humans

Abstract

The internal areas and the position of integration of the glycopeptide resistance element Tn1546 were characterized by using PCR fragment length polymorphism, sequencing, and DNA hybridization techniques with 38 high-level vancomycin-resistant Enterococcus faecium isolates of human and animal origins from Europe and the United States. Only minor variations in the coding regions within Tn1546 were found, suggesting high genetic stability. The isolates originated from broilers (n = 5), a chicken (n = 1), a duck (n = 1), a turkey (n = 1), pigs (n = 8), a pony (n = 1), and humans (n = 23). A total of 13 different types were defined based on a single-nucleotide difference in the vanXgene, the presence of insertion sequences, and hybridization patterns. For some types more than one isolate were found. For type 1, 10 isolates of both human and animal origins were 1found. All were indistinguishable from the reference strain, BM4147. For type 2, 11 isolates of human and animal origins were found. Six human isolates from England were all of type 3. Two human isolates from the United States, indistinguishable from each other, were type 9. These results showed that vancomycin-resistant E. faecium of animal and human origins can contain indistinguishable genetic elements coding for vancomycin resistance, indicating either horizontal gene transfer between E. faecium organisms of human and animal origins or the existence of a common reservoir for glycopeptide resistance.

Detection of the satA gene and transferability of virginiamycin resistance in Enterococcus faecium from food-animals

“…The satA-positive strains were hybridized with the satA probe. Pulsed ¢eld gel electrophoresis (PFGE) of the donors and transconjugants was performed according to Jensen et al [21].…”

Internal size variations in Tn1546-like elements due to the presence of IS1216V

“…Among the 12 isolates tested were a group of isolates previously described to contain similar Tn1546like elements identi¢ed by a combination of sequencing and DNA hybridization [11]. By determination of the exact point of integration, small variations among these type 3 Tn1546-like elements were found (Fig.…”

“…There were seven isolates of human origin from the United Kingdom, one poultry isolate from Denmark and three poultry and one human isolate from the Netherlands. All isolates except K36syn and K38v have been described previously [9,11]. K36syn and K38v have non-identical PFGE patterns and were kindly provided by Dr. A.E.M.…”

“…They originated from a collection of VRE isolated from animals in the Netherlands [16]. All isolates contained Tn1546-like elements with unknown size variations in the internal vanX^vanZ area of Tn1546 as identi-¢ed when hybridized with DNA probes [11].…”

“…Total DNA extraction and PCR ampli¢cation were performed as previously described [11]. For each isolate, total DNA was extracted from two independent colonies and primers listed in Table 1 were used for ampli¢cation.…”