Aortic valve endocarditis in a dog due to Bartonella clarridgeiae

Abstract

We report the first documented case of endocarditis associated with Bartonella clarridgeiae in any species. B. clarridgeiae was identified as a possible etiological agent of human cat scratch disease. Infective vegetative valvular aortic endocarditis was diagnosed in a 2.5-year-old male neutered boxer. Historically, the dog had been diagnosed with a systolic murmur at 16 months of age and underwent balloon valvuloplasty for severe valvular aortic stenosis. Six months later, the dog was brought to a veterinary hospital with an acute third-degree atrioventricular block and was diagnosed with infective endocarditis. The dog died of cardiopulmonary arrest prior to pacemaker implantation. Necropsy confirmed severe aortic vegetative endocarditis. Blood culture grew a fastidious, gram-negative organism 8 days after being plated. Phenotypic and genotypic characterization of the isolate, including partial sequencing of the citrate synthase (gltA) and 16S rRNA genes indicated that this organism was B. clarridgeiae. DNA extraction from the deformed aortic valve and the healthy pulmonic valve revealed the presence of B. clarridgeiae DNA only from the diseased valve. No Borrelia burgdorferi or Ehrlichia sp. DNA could be identified. Using indirect immunofluorescence tests, the dog was seropositive for B. clarridgeiae and had antibodies against Ehrlichia phagocytophila but not against Ehrlichia canis, Ehrlichia ewingii, B. burgdorferi, or Coxiella burnetii.

FIG. 1

Electrocardiogram showing third-degree AV block. Paper speed, 50 mm/s; gain, 10 mm/mV.

FIG. 2

Two-dimensional echocardiograms recorded in right parasternal long axis (A) or short axis basilar (B), showing aortic valve proliferative lesions (arrows) characteristic of infective endocarditis. LA, left atrium; Ao, Aorta; RV, right ventricle. LV, left ventricule.

FIG. 3

(A) Gross pathological specimen of aortic valve vegetative endocarditis. (B) Gross pathological specimen (close-up) of aortic valve endocarditis showing vegetative lesions.

FIG. 4

PCR (lanes 2 to 6) and PCR-RFLP (lanes 8 to 12, TaqI digestion; lanes 13 to 17, HhaI digestion) analysis of the gltA gene. Lanes 1, 8, and 13, B. henselae (strain U4, UC Davis); lanes 2, 9, and 14, B. clarridgeiae ATCC 57134; lanes 3, 10, and 15, B. vinsonii subsp. berkhoffii ATCC 51672; lanes 4, 11, and 16, dog isolate UCD-dog1; lanes 5, 12, and 17, DNA extracted from the aortic valve; lane 6, DNA extracted from the pulmonic valve; lanes 7 and 18, standard 100-bp molecular ladder.