Bartonella chomelii Is the Most Frequent Species Infecting Cattle Grazing in Communal Mountain Pastures in Spain

The presence ofBartonella spp. was investigated in domestic ungulates grazing in communal pastures from a mountain area in northern Spain, where 18.3% (17/93) of cattle were found to be positive by PCR combined with a reverse line blot (PCR/RLB), whereas sheep (n = 133) or horses (n = 91) were found not to be infected by this pathogen.Bartonella infection was significantly associated with age, since older animals showed a higher prevalence than heifers and calves. In contrast to other studies,B. chomelii was the most frequent species found in cattle (14/17), whileB. bovis was detected in only three animals. Moreover, 18B. chomelii isolates and oneB. bovis isolate were obtained from nine animals. Afterwards,B. chomelii isolates were characterized by a multilocus sequence typing (MLST) method which was adapted in this study. This method presented a high discrimination power, identifying nine different sequence types (STs). This characterization also showed the presence of different STs simultaneously in the same host and that STs had switched over time in one of the animals. In addition,B. chomelii STs seem to group phylogenetically in two different lineages. The onlyB. bovis isolate was characterized with a previously described MLST method. This isolate corresponded to a new ST which is located in lineage I, where theB. bovis strains infectingBos taurus subsp.taurus are grouped. Further studies on the dynamics ofBartonella infection in cattle and the potential ectoparasites involved in the transmission of this microorganism should be performed, improving knowledge about the interaction ofBartonella spp. and domestic ungulates.