title: Presence of Coxiella burnetii DNA in inflamed bovine cardiac valves.
abstract: BACKGROUND
  Bacterial endocarditis is a recognised disease in humans and animals. In humans, infection with Coxiella burnetii can cause endocarditis, but this has not been investigated thoroughly in animals. Endocarditis in cattle is a common post-mortem finding in abattoirs and studies have identified Trueperella pyogenes as a major cause. Despite exposure of cattle to C. burnetii, the significance of this particular bacterium for development and progression of endocarditis has not been studied in detail. Cardiac valves of cattle affected with endocarditis (n = 100) were examined by histology, fluorescence in situ hybridization (FISH) and real time quantitative polymerase chain reaction (PCR). Serum was examined for anti-C. burnetii antibodies by enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  Serology revealed that 70% of the cattle were positive for antibodies to C. burnetii, while PCR analysis identified 25% of endocarditis valve samples as being positive. C. burnetii was not detected by FISH, probably due to the low infection levels. Most cattle had chronic valvular vegetative endocarditis with lesions being characterised by a core of fibrous tissue covered by significant amounts of fibrin, sometimes with areas of liquefaction, and with a coagulum covering the surface. In a few cases, including the case with the highest infection level, lesions were characterized by extensive fibrosis and calcification. Histologically, bacteria other than C. burnetii were observed in most cases.
  
  
  CONCLUSIONS
  The presence of C. burnetii DNA is relatively common in cattle affected with valvular endocarditis. The role of C. burnetii remains however unknown as lesions did not differ between C. burnetii infected and non-infected cattle and because T. pyogenes-like bacteria were present in the inflamed valves; a bacterium able to induce the observed lesions. Heart valves of normal cattle should be investigated to assess if C. burnetii may be present without preexisting lesions.
authors.affiliation: Department of Large Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Hojbakkegaard Alle 5, DK-2630, Taastrup, Denmark. jager@sund.ku.dk.
authors.forename: Jørgen S
authors.initials: JS
authors.lastname: Agerholm
authors.affiliation: National Veterinary Institute, Technical University of Denmark, Bülowsvej 27, DK-1870, Frederiksberg C, Denmark.
authors.forename: Tim K
authors.initials: TK
authors.lastname: Jensen
authors.affiliation: Department of Large Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Hojbakkegaard Alle 5, DK-2630, Taastrup, Denmark.
authors.forename: Jens F
authors.initials: JF
authors.lastname: Agger
authors.affiliation: Department of Diagnostics and Crisis Organisation, Wageningen Bioveterinary Research, Edelhertweg 15, 8219 PH, Lelystad, The Netherlands.
authors.forename: Marc Y
authors.initials: MY
authors.lastname: Engelsma
authors.affiliation: Department of Bacteriology and Epidemiology, Wageningen Bioveterinary Research, Edelhertweg 15, 8219 PH, Lelystad, The Netherlands.
authors.forename: Hendrik I J
authors.initials: HI
authors.lastname: Roest
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D016997:Coxiella burnetii / Q000235:genetics*; D004269:DNA, Bacterial / Q000302:isolation & purification*; D004697:Endocarditis, Bacterial / Q000382:microbiology / Q000662:veterinary*; D005260:Female; D006351:Heart Valves / Q000382:microbiology*; D007249:Inflammation / Q000382:microbiology / Q000662:veterinary; D008297:Male; D011778:Q Fever / Q000382:microbiology / Q000662:veterinary*
chemical_list: D000907:Antibodies, Bacterial; D004269:DNA, Bacterial
keywords: Cattle; Coxiella burnetii; Endocarditis; PCR; Q fever