The role of Streptococcus zooepidemicus persister cells during endometritis in the natural equine host.

Streptoccocus equi subspecies zooepidemicus (S. zooepidemicus) is an opportunistic pathogen colonizing the mucus membranes of various animal species, yet it has also remained the most frequent cause of endometritis and lowered breading efficacy in mares for decades.

Recently, S. zooepidemicus was found to cause persister-like infections deep within the endometrium of mares despite antimicrobial treatment and a fully functional endometrial immune system.

In this project, we are investigating the formation and regulation of S. zooepidemicus persisters. In general, bacterial persister cells are thought to enter a slow-growing or dormant state, making them tolerant to antibiotic treatment and other environmental stress factors. In this project, we aim to isolate persistent S. zooepidemicus cells in vitro and characterize the mechanisms involved in the formation and re-activation of those persisters. Moreover, we investigate and verify the mechanism of persistence in vivo through experimental inoculation of mares.

For more information, please contact Bolette Skive ( ) or Anders Miki Bojesen ( ).

Pictures kindly lent out by Millhorse AB ( Picture of S. zooepidemicus colonies taken by Bolette.

Recent publications

The role of Streptococcus zooepidemicus persister cells during endometritis in the natural equine host: Kudirkiene, E, Welker, M, Knudsen, NR & Bojesen, AM 2015, 'Rapid and accurate identification of Streptococcus equi subspecies by MALDI-TOF MS' Systematic and Applied Microbiology., doi: 10.1016/j.syapm.2015.02.010

Petersen, M.R., K. Lu, M. Christoffersen, J. M. Nielsen, M. H. Troedsson, A. M. Bojesen. Impact of activation and subsequent antimicrobial treatment of dormant endometrial streptococci in the Thoroughbred problem mare – a descriptive field study. Proceeding from the annual meeting in The Society for Theriogenology, 7th-10th August. 2013, Louisville, Kentucky, USA.  

Da Piedade, I., B. Skive, H. Christensen, A. M. Bojesen. Draft genome sequence for Streptococcus equi subspecies zooepidemicus, strain S31A1 isolated from equine infectious endometritis. Genome Announcements. Genome Announc. 2013, 1(5):e00683-13. doi:10.1128/genomeA.00683-13.

Rasmussen, C. B., M. M. Haugaard, M. R. Petersen, J. M. Nielsen, H. G. Pedersen, A. M. Bojesen. Streptococcus equi subsp. zooepidemicus isolates from equine infectious endometritis belong to a distinct genetic group. Veterinary Research. 2013, 44, 26.

Skive, B., M. R. Petersen, A. M. Bojesen. Real-Time PCR’s anvendelse til diagnostik af endometritis hos hopper. Dansk Veterinær Tidsskrift. 2012, 1, 20-25.

Bisgaard, M., A. M. Bojesen, M. R. Petersen, H. Christensen. A major outbreak of Streptococcus equi subsp. zooepidemicus infections in free-range chickens is linked to horses. Avian Diseases. 2012, 56, 561-566.

Christoffersen, M., E. M. Woodward, A. M. Bojesen, M. R. Petersen, E. L. Squires, H. Lehn-Jensen, M. H. Troedsson. Effect of immunomodulatory therapy on the endometrial inflammatory response to induced infectious endometritis in susceptible mares. Theriogenology. 2012, 78, 991-1004.

Christoffersen, M., E. M. Woodward, A. M. Bojesen, S. Jacobsen, M. R. Petersen, M. Troedsson, H. Lehn-Jensen. Inflammatory responses to infectious endometritis in mares resistant or susceptible to persistent endometritis. BMC Veterinary Research. 2012, 8, 41.

Christoffersen, M., C.D. Baagoe, S. Jacobsen, A.M. Bojesen, M. R. Petersen, H. Lehn-Jensen. Evaluation of the systemic acute phase response and endometrial gene expression of serum amyloid A and pro- and anti-inflammatory cytokines in mares with experimentally induced endometritis. Veterinary Immunology and Immunopathology. 2010, 138, 95-105.                                                          

 Nielsen, J. M.,W. Zent, M. M. Petersen, A. M. Bojesen, H. Lehn-Jensen, M. Troedsson. Diagnosis of endometritis in the mare based on bacteriological and cytological examinations of the endometrium. Comparison of results obtained by swabs and biopsies. Journal of Equine Veterinary Science. 2010, 30, 27-30.

Petersen, M. R., J. M. Nielsen, H. Lehn-Jensen, A. M. Bojesen. Streptococcus equi subspecies zooepidemicus resides deep in the chronically infected endometrium of mares. Clinical Theriogenology. 2009, 393-409.