Successful treatment of canine infective endocarditis caused by Bacillus amyloliquefaciens

Area of Science:

• Veterinary Medicine
• Infectious Diseases
• Microbiology

Background:

• Bacillus amyloliquefaciens is a Gram-positive bacterium recognized for its probiotic applications in both human and animal health.
• Infective endocarditis (IE) is a rare condition in veterinary medicine, with no prior documented cases in dogs attributed to Bacillus amyloliquefaciens.

Observation:

• An 8-year-old female Maltese dog presented with a month-long history of fever, depression, weight loss, and hindlimb lameness.
• Diagnostic workup revealed non-regenerative anemia, neutrophilia, hyperglobulinemia, and proteinuria.
• Echocardiography identified vegetation on the mitral valve's septal leaflet and left atrial thromboemboli.

Findings:

• Blood cultures consistently identified Bacillus amyloliquefaciens, a species typically considered benign and probiotic.
• The dog received a 4-month course of broad-spectrum antibiotics (amoxicillin-clavulanic acid and cefotaxime) and anticoagulants (clopidogrel and rivaroxaban).
• Clinical signs improved with antibiotic therapy, fever resolved, left atrial thromboemboli reduced in size, and bacteria were eradicated from blood cultures.

Implications:

• This report highlights a novel cause of infective endocarditis in canines, expanding the spectrum of known Bacillus amyloliquefaciens-associated diseases.
• It underscores the importance of considering less common bacterial pathogens, even those with probiotic use, in cases of canine endocarditis.
• Successful treatment with antibiotics demonstrates the efficacy of conventional antimicrobial therapy for this specific type of IE.