High diversity of Tn1546 among vancomycin-resistant enterococci from Portuguese human, animal and environmental sources

Abstract number: 902_p814

Novais C.


To characterise the diversity of the genetic element Tn1546 in vancomycin resistant enterococcal (VRE) isolates recovered from different sources in different Portuguese regions.


VRE were searched in different sources from the North and Centre of Portugal (1996–2003): (i) 99 poultry samples (P) for human consumption, (ii) 37 swine faeces (S), (iii) six river water samples (R), (iv) 32 samples collected upstream and downstream hospital sewage water (SW), (v) 99 faecal samples from healthy volunteers (HV), (vi) clinical isolates from three hospitals in three cities (H). Identification and characterisation of vancomycin resistant genes vanA, vanB, vanC1 and vanC2 were determined by a multiplex PCR. Tn1546-typing was performed by scoring the presence of 10 overlapping fragments, using a PCR assay.


One hundred and two isolates showing vanA were identified (63 E. faecium, 35 E. faecalis and four Enterococcus spp.). Sixteen Tn1546 variants were detected. The most common ones were variant A (indistinguishable to Tn1546), and variant PP4 (with an ISEfm1 insertion in the intergenic region of vanY-vanZ) which were found in 16 and 22% of the isolates, respectively. Variant A was recovered from P, S and H samples while PP4 was only found in human samples. Ten Tn1546 variants lack amplicons with primers corresponding to regions associated with transposition functions and 12 variants had alterations in regions downstream vanA. These include insertions in the vanY-vanZ (n = 3) or vanX-vanY (n = 3) regions. Four Tn1546 variants have been already described [groups A, D (HV,P,S), E (P) and S (P)]. Nine of 16 Tn1546 types were detected in different enterococcal species. Three Tn1546 types were only found in human, three in animals and humans, one in animals, humans and rivers, two in humans and river and two found in both humans and sewage.


High diversity of Tn1546 was observed among Portuguese VRE. Variable distribution of Tn1546 variants suggests both local availability of specific types in local metagenomes and dissemination of specific genetic elements among different reservoirs. Reasons underlying Tn1546 diversity needs further research.


Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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