Poster Presentation International Pasteurellaceae Conference 2014

Analysis and comparison of the first integrative and conjugative element (ICE) of Mannheimia haemolytica, the ICEMh1 (#46)

Christopher Eidam 1 , Anja Poehlein 2 , Andreas Leimbach 2 , Geovana Brenner Michael 1 , Heiko Liesegang 2 , Kristina Kadlec 1 , Rolf Daniel 2 , Michael T. Sweeney 3 , Robert W. Murray 3 , Jeffrey L. Watts 3 , Stefan Schwarz 1
  1. Friedrich-Loeffler-Institut (FLI), Neustadt Am Ruebenberge, Germany
  2. Department of Genomic and Applied Microbiology, Goettingen Genomics Laboratory, Goettingen, Germany
  3. Zoetis, Kalamazoo, MI, USA

Mannheimia haemolytica is considered the major bacterial agent of the multifactorial bovine respiratory disease (BRD) complex, which results in a loss of over three billion U.S. dollars per year for the global cattle industry. Antimicrobial agents are commonly used to treat cattle that suffer from BRD. During recent years, a growing number of isolates showed resistance to one or more antimicrobial agents. Integrative and conjugative elements (ICEs), like the recently described ICEPmu11,2, may play a role as reservoirs for and distributers of antimicrobial resistance genes in Pasteurellaceae.

The M. haemolytica strain 42548 was subjected to whole genome sequencing3, followed by sequence analysis and comparative genomics.

One ICE was identified in M. haemolytica strain 42548 and designated ICEMh1. The ICEMh1 has a size of 92345 bp and harbours 107 open reading frames. ICEMh1 integrates into a tRNALeu in the chromosome. Additionally, it is able to transfer to P. multocida by conjugation. PCR assays confirmed the presence of the ICEMh1-associated resistance genes in the recipient strains. Within two resistance regions, approximately 7.4 kp and 3.3 kb in size, ICEMh1 harbours five resistance genes, which confer resistance towards streptomycin (strA and strB), kanamycin/neomycin (aphA1), tetracycline [tetR-tet(H)] and sulphonamides (sul2).

ICEMh1 is closely related to the ICEPmu1 and seems to have evolved from a common predecessor. A region of ICEMh1 that is not present in ICEPmu1, can be found in putative ICE regions of other M. haemolytica genomes, suggesting a recombination event of two ICEs. These findings support the observation that ICEs can easily spread, even across genus borders, allowing for the acquisition of multidrug-resistant profiles via a single horizontal gene transfer event. This poses a threat to therapeutic antimicrobial strategies in all fields, not only for the treatment of BRD.

  1. Michael GB, Kadlec K, Sweeney MT, Brzuszkiewicz E, Liesegang H, Daniel R, Murray RW, Watts JL, Schwarz S. 2012. ICEPmu1, an integrative conjugative element (ICE) of Pasteurella multocida: analysis of the regions that comprise 12 antimicrobial resistance genes. J. Antimicrob. Chemother. 67:84–90.
  2. Michael GB, Kadlec K, Sweeney MT, Brzuszkiewicz E, Liesegang H, Daniel R, Murray RW, Watts JL, Schwarz S. 2012. ICEPmu1, an integrative conjugative element (ICE) of Pasteurella multocida: structure and transfer. J. Antimicrob. Chemother. 67:91–100.
  3. Eidam C, Poehlein A, Michael GB, Kadlec K, Liesegang H, Brzuszkiewicz E, Daniel R, Sweeney MT, Murray RW, Watts JL, Schwarz S. 2013. Complete genome sequence of Mannheimia haemolytica strain 42548 from a case of bovine respiratory disease. Genome Announc. 1:2010–2011.