HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplementary Material Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Moyaert, H. Articles by Haesebrouck, F. Search for Related Content PubMed PubMed Citation Articles by Moyaert, H. Articles by Haesebrouck, F. Agricola Articles by Moyaert, H. Articles by Haesebrouck, F.

Helicobacter equorum sp. nov., a urease-negative Helicobacter species isolated from horse faeces

¹ Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium
² Department of Biochemistry, Physiology and Microbiology, Faculty of Sciences, Ghent University, Ledeganckstraat 35, B-9000 Ghent, Belgium
³ CODA – CERVA – VAR, Groeselenberg 99, B-1180 Brussels, Belgium

Correspondence
H. Moyaert
Hilde.Moyaert{at}UGent.be

Gram-negative, curved, motile bacteria (strains EqF1^T and EqF2) were isolated from faecal samples from two clinically healthy horses. Both strains possessed a single, monopolar, sheathed flagellum and were urease-negative. The novel strains grew at 37 °C under microaerobic conditions and were positive for oxidase, catalase and alkaline phosphatase activities. The isolates reduced nitrate to nitrite, but -glutamyl transpeptidase activity was not detected. The novel isolates did not grow at 42 °C or on media containing 1 % glycine. They were resistant to cephalotin and nalidixic acid and susceptible to metronidazole. Analysis of the 16S and 23S rRNA gene sequences of the two novel strains identified them as representing a single species within the genus Helicobacter. In terms of 16S rRNA gene sequence similarity, Helicobacter pullorum and Helicobacter canadensis were the most closely related species (98 % similarity). 23S rRNA gene sequence analysis also classified strains EqF1^T and EqF2 within the enterohepatic division of the genus Helicobacter, but only 94 % similarity was detected with H. pullorum and H. canadensis, which are helicobacters with unsheathed flagella. The most closely related species in terms of 23S rRNA gene sequence similarity was Helicobacter canis (95 %). Numerical analysis of whole-cell protein extracts by SDS-PAGE was performed and the novel isolates were clearly differentiated from H. pullorum, H. canadensis, H. canis and other species of the genus Helicobacter. This finding was also confirmed by sequence analysis of the hsp60 gene. On the basis of these genetic, biochemical and protein data, the isolates are classified as representing a novel species, for which the name Helicobacter equorum sp. nov. is proposed (type strain EqF1^T=LMG 23362^T=CCUG 52199^T).

Figures showing transmission electron microscope images of cells of strains EqF1^T and EqF2 and phylogenetic trees based on 16S rRNA, 23S rRNA and hsp60 gene sequences are available as supplementary material in IJSEM Online. Distance matrix analyses for the three genes are available as supplementary tables.