Identification of Streptococcus suis in a cat with endomyocarditis

CASE SUMMARY: A 3-year-old neutered male domestic mediumhair cat was evaluated for a 4-month history of a fever that was responsive to pradofloxacin. A grade III/VI left parasternal systolic heart murmur was noted on examination. Findings on thoracic radiography were consistent with left-sided congestive heart failure and findings on echocardiographic examination suggested endomyocarditis. Aerobic blood cultures yielded growth of a Streptococcus species that was identified as Streptococcus suis using both matrix-associated laser desorption ionization-time of flight mass spectrometry and 16S rRNA gene sequencing. The cat was treated but clinically deteriorated and was euthanized 23 days after diagnosis. RELEVANCE AND NOVEL INFORMATION: To our knowledge, this is the first report of S suis bacteremia, an emerging pathogen, in association with endomyocarditis in the cat. This case also highlights the role of echocardiography to document progressive hemodynamic changes as a result of valvular erosion in the course of infective endocarditis treatment and the role of blood cultures as a diagnostic tool in cats presenting with fever.