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J. Clin. Microbiol. doi:10.1128/JCM.00867-08
Copyright (c) 2008, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Helcococcus ovis, an emerging pathogen in bovine valvular endocarditis

Landeslabor Brandenburg, 15236 Frankfurt (Oder), Germany; Institut für Mikrobiologie und Tierseuchen, Freie Universität Berlin, 10115 Berlin, Germany

^* To whom correspondence should be addressed. Email: peter.kutzer{at}llb.brandenburg.de.

	Abstract

The initial isolation of Helcococcus ovis from a valvular thrombus prompted us to investigate the prevalence of this bacterium in bovine valvular endocarditis. Specimens from 55 affected hearts were examined by culture using Columbia blood agar and cross streaking the inoculated plate with a Staphylococcus aureus strain. As confirmed by 16S rRNA gene sequencing, H. ovis was isolated with unexpected high frequency of 33%, predominantly as heavy growth and pure culture. The majority of H. ovis isolates showed distinct satellitism around S. aureus and pyridoxal dependency, resembling "nutritionally variant streptococci" (NVS) actually designated to the genera Abiotrophia and Granulicatella. Using the API rapid ID 32 Strep, API ZYM and Rosco Diatabs systems, incongruent results were obtained for alkaline phosphatase, -galactosidase, -glucuronidase and leucine aminopeptidase activity. Based on the characteristics satellitism/pyridoxal dependency, hemolysis on blood agar and the API rapid ID 32 Strep results for arginine dihydrolase, -galactosidase, -galactosidase, -glucuronidase and pyroglutamic acid arylamidase activity, hippurate hydrolysis and acidification of sucrose, a scheme for the identification of H. ovis and its differentiation from other members of the Helcococcus genus and the pyridoxal-dependent species Abiotrophia defectiva, Granulicatella adiacens and Granulicatella elegans is proposed. By establishing specific fluorescence in situ hybridization, large H. ovis aggregates were specifically detected within the fibrinous exsudate of the valvular thrombi. Our results demonstrate for the first time that H. ovis represents an emerging pathogen in bovine valvular endocarditis, frequently isolated if appropriate culture conditions are used.