CPB 697 RESEARCH SEMINAR
Robert Johnson, DVM
Graduate Student in Anatomic Pathology
Department of
“Identification of Bartonella Hanselae in
an Aborted Equine Fetus”
R. Johnson, J. Ramos-Vara, and R. Vemulapalli
Thursday, November 8, 2006
VPTH 112 - 3:30
p.m.
ABSTRACT:
Bartonella henselae is a Gram-negative bacterium that often causes an asymptomatic bacteremia, but can cause cat scratch disease, bacillary angiomatosis, bacillary peliosis, and endocarditis. The bacterium has been isolated from numerous mammalian species, but not from equids. An aborted equine fetus exhibited gross and histologic evidence of necrosis and vasculitis in multiple tissues with intralesional spirochete-like organisms. The intralesional organism is Gram-negative and varies from short rods to wavy, spirilar forms up to 5 um long in Warthin-Starry stained sections. Using universal primers, the bacterial 16S rRNA gene was amplified from DNA extracted from fetal lung, spleen, and kidney. Nucleotide sequence of the amplified PCR product revealed 99.9% identity to the 16S rRNA gene of Bartonella henselae. Identification was confirmed using other Batronella spp. gene primers. Microorganisms were immunohistochemically labeled with monoclonal Bartonella henselae antibody. Ultrastructurally, organisms are irregularly coiled, but distinct periplasmic flagella are not apparent. Leptospirosis was excluded by negative leptospira culture, negative PCR, and negative immunohistochemistry. Borrelia spp. have also been reported as a cause of equine abortion, but multiple attempts to amplify Borrelia-specific DNA via PCR using primers targeting the 16S rRNA and flagellin genes were unsuccessful. EHV fluorescent antibody tests, virus isolation, and bacterial culture were all negative. To our knowledge, this is the first reported identification of Bartonella henselae in an equid. Given the severity of vasculitis and association of the bacterium with lesions, we conclude that Bartonella henselae caused the abortion of this foal.