First molecular characterization of a granulocytic Ehrlichia strain isolated from a dog in South Italy

The 5-year-old bitch boxer came from an area where ticks are endemic and was referred to the Department of Veterinary Clinical Sciences, Faculty of Veterinary Medicine, University of Napoli Federico II (Italy) with clinical signs of acute lameness of the right forelimb, fever (39.7 _C) and dysorexia. Routine haematology and serum biochemistry gave results in the normal range, but leukocytosis (13,000 cells/lL) with absolute neutrophilia, thrombocytopenia (16,0000/lL) and mild anaemia were recorded. Microscope analysis of blood smears stained with Giemsa revealed granulocytic inclusion bodies identified as Ehrlichia spp. organisms. Clinical, haematological, and serological data as well as the morphology of the causative agent are not sufficient for the differentiation of closely related members of the E. phagocytophila genogroup. Molecular analysis is the method of choice for the identification and classification of bacteria that cannot be cultured or characterized by conventional techniques. A blood sample (5 mL) collected in ethylenediamine tetra-acetic acid (EDTA) was used for extraction of ehrlichial DNA. The phylogenetic analysis showed that the new isolated Ehrlichia spp. from the Italian dog is positioned in the E. phagocytophila genogroup (Fig. 2, Panel A). The nucleotide sequence of the Italian Ehrlichia isolate was similar to those of E. equi, E. phagocytophila and HE (identity 98%), and was less related to E. ewingii, E. canis, and E. sennetsu (Fig. 2, Panel B).