Poster Presentation MedVetPATHOGENS 2018

Three distinct but related tetracycline resistance plasmids encoding tet(B) in isolates of Actinobacillus pleuropneumoniae (#109)

Yinghui Li 1 , Giarlã C da Silva 2 , Yanwen Li 1 , Ciro C Rossi 2 , Roberto Fernandez Crespo 1 , Susanna M Williamson 3 , Paul R Langford 1 , Denise MS Bazzolli 2 , Janine T Bosse 1
  1. Department of Medicine, Imperial College London, London, UK
  2. Laboratório de Genética Molecular de Bactérias, Departamento de Microbiologia, Universidade Federal de Viçosa, Viçosa, Brazil
  3. Animal Health and Veterinary Laboratories Agency (AHVLA), Bury St Edmunds, UK

Resistance to tetracycline is widespread amongst isolates of the porcine pathogen Actinobacillus pleuropneumoniae (APP). Evidence of plasmids carrying the tetracycline resistance gene, tet(B), was found in the previously reported whole genome sequences (wgs) of fourteen UK, and four Brazilian, APP isolates. As small plasmids often appear to be common amongst members of the Pasteurellaceae, the aim of this study was to identify the tet(B) plasmids present in these sequenced isolates of A. pleuropneumoniae.

 

BLASTn was used to identify sequences with the highest identity to each of the tet(B)-carrying contigs found in the draft wgs. Where it appeared that the contigs carrying tet(B) represented only partial plasmids, sequences of the plasmids with highest identity were then used to search the wgs using BLASTn to identify other contigs carrying plasmid-related sequences. Plasmids were extracted from representative isolates, and their complete sequences were confirmed using a primer walking strategy.

 

We identified three different tet(B) plasmids in the APP isolates in this study. The Brazilian isolates carry a 5128 bp plasmid identical to pB1001 previously identified in Pasteurella multocida. Thirteen UK isolates were found to contain plasmids (3366 to 3386 bp) almost identical to pTetHS016 from Haemophilus parasuis. The remaining UK isolate harbours a 12666 bp plasmid that shares extensive regions of similarity with pOV from P. multocida, which carries blaROB-1, sul2 and strAB genes, as well as with pTetHS016. The newly identified multi-resistance plasmid, pM3362MDR, appears to have arisen through illegitimate recombination of a pTetHS016-like plasmid into the stop codon of the strB gene in pOV. Comparison of pB1001 and pTetHS016 revealed that the they share 95% identity over the majority of the smaller sequence, indicating that all of the plasmids detailed in this study are related, and likely evolved from the same origin.

  1. Bossé, J. T., Li, Y., Rogers, J., Fernandez Crespo, R., Li, Y., Chaudhuri, R. R., et al. (2017). Whole genome sequencing for surveillance of antimicrobial resistance in Actinobacillus pleuropneumoniae. Front. Microbiol. 8:311.
  2. Pereira, M. F., Rossi, C. C., de Carvalho, F. M., de Almeida, L. G. P., Souza, R. C., de Vasconcelos, A. T. R., et al. (2015). Draft genome sequences of six Actinobacillus pleuropneumoniae serotype 8 Brazilian clinical isolates: insight into new applications. Genome Announc. 3:e01585–14.