Helcococcus ovis, an emerging pathogen in bovine valvular endocarditis

Area of Science:

• Veterinary Microbiology
• Bacterial Pathogenesis
• Molecular Diagnostics

Background:

• Bovine valvular endocarditis is a significant concern in cattle health.
• The causative agents of bovine endocarditis are not fully understood.
• Helicoccus ovis was initially isolated from a valvular thrombus, suggesting a potential role in this condition.

Purpose of the Study:

• To investigate the prevalence of Helicoccus ovis in bovine valvular endocarditis.
• To develop an accurate identification scheme for H. ovis and differentiate it from related species.
• To confirm the presence of H. ovis in affected cardiac tissues.

Main Methods:

• Culture of cardiac specimens on Columbia blood agar with Staphylococcus aureus cross-streaking.
• 16S rRNA gene sequencing for bacterial identification.
• Biochemical characterization using API systems (Rapid ID 32 Strep, ZYM) and Rosco Diatabs.
• Fluorescence in situ hybridization (FISH) for in situ detection.

Main Results:

• Helicoccus ovis was isolated from 33% of bovine valvular endocarditis cases, often in pure, heavy cultures.
• Most isolates exhibited satellitism around S. aureus and pyridoxal dependency.
• A proposed identification scheme effectively differentiated H. ovis from Abiotrophia and Granulicatella species.
• FISH confirmed the presence of large H. ovis aggregates in valvular thrombi.

Conclusions:

• Helicoccus ovis is an emerging and frequently isolated pathogen in bovine valvular endocarditis.
• Appropriate culture techniques, including satellitism with S. aureus, are crucial for H. ovis isolation.
• The developed identification scheme aids in accurate diagnosis and differentiation of H. ovis.