Fachbereich Veterinärmedizin



    Population Structure of MRSP and MSSP in Germany:
    A Genomic Approach (2015)

    Semmler, Torsten
    Luebke-Becker, Antina (WE 7)
    Stamm, I
    Brandenburg, A
    Corander, J
    Abou-Elnaga, Yassmin (WE 7)
    Wieler, LH
    Walther, Birgit (WE 7)
    4th ASM-ESCMID Conference on Methicillin-resistant Staphylococci in Animals: Veterinary and Public Health Implications
    Chicago, Illinois, 02. – 05.11.2015
    4th ASM-ESCMID Conference on Methicillin-resistant Staphylococci in Animals: Veterinary and Public Health Implications ; November 2 – 5, 2015 Chicago, Illinois ; Final Program and Abstracts — American Society for Microbiology (Hrsg.)
    Washington, DC, 2015 — S. 25–26
    URL (Volltext): http://conferences.asm.org/images/mrsa2015finalprogram.pdf
    Institut für Mikrobiologie und Tierseuchen

    Robert-von-Ostertag-Str. 7-13
    Gebäude 35
    14163 Berlin
    Tel.+49 30 83 8-518 40/518 43 Fax.+49 30 838 45 18 51

    Abstract / Zusammenfassung

    Introduction: In veterinary medicine, infections with methicillin resistant Staphylococcus pseudintermedius (MRSP) are a global therapeutic challenge. MRSP are often associated with a multidrug resistant phenotype and therefore difficult to treat successfully. In addition, MRSP are typical nosocomial pathogens tending to spread within veterinary clinical settings. During a risk assessment study in Germany, 100 MRSP and 100 methicillin
    susceptible S. pseudintermedius isolates have been collected from various geographic origins, clinical settings and animal patient histories. Based on PFGE pattern and epidemiological data we chose 108 representative strains from both groups for whole genome
    sequencing (WGS) to get an insight into the composition and phylogenetic relationship of
    clinical relevant S. pseudintermedius strains in Germany. Methods: Species identity was
    confirmed by NCBI-blast for housekeepinggenes pta and cpn60. Based on the Maximum
    Common Genome (MCG, von Mentzer etal., Nat. Gen. 2014) a maximum likelihood
    (ML)-phylogeny was calculated with the maximum resolution. In addition, the amount
    and distribution of recombination events was analyzed with Bayesian Recombination
    Tracker (BRAT) and the distribution of the accessory genes clustered for similarity within
    the selected genomes. Further zoom into the MRSP-ST71 group was performed to gain insight into the microevolution of this successful lineage. Results: The MCG determined for 108 S. pseudintermedius (55 MRSP, 53 MSS isolates comprised 1.909 orthologous genes. Bootstrap analysis indicated a diverse phylogenetic background: Beside genomes of isolates sharing the same ST, no significant clustering could be detected. All genomes showed a more or less comparable distance to a common ancestor. This observation was also confirmed by distribution analysis of the accessory gene content. Overall, the genomes showed rather
    limited recombination together with an evenly distribution of these events over the genome,
    lacking a certain cluster-specific variation. Among MRSP reported on here, those belonging
    to sequence type (ST)71 predominated (> 80%). These MRSP-ST71 genomes share a
    MCG of 2.308 orthologous genes and were not as similar as one would expect. Although numerous genetic variations were detected, they did not unravel any significant host or
    geographic association. Discussion: The investigated S. pseudintermedius population is
    remarkably diverse. Within this diversity the genomic ST71 background seems to have an
    evolutionary advantage as these strain are the most frequent detected population subgroup.
    As all ST71 strains contain the mec complex, but are clonally divers, their spread is not due to clonal expansion. Whether the content of mobile genetic elements or other factors are responsible for their successful spread requires further investigation.