Helicobacter winghamensis sp. nov., a novel Helicobacter sp. isolated from patients with gastroenteritis

Abstract

From 1997 to 1999 seven isolates of Campylobacter-like organisms from five patients that were exhibiting symptoms of gastroenteritis, including fever, stomach malaise, and diarrhea, were investigated. The organisms were isolated from stool samples and found to exhibit a diverse colony morphology; hence multiple isolates were submitted from one of the patients. All isolates were found to be identical. The organisms were catalase, urease, alkaline phosphatase, and nitrate negative but oxidase and indoxyl acetate positive. They grew at 37 degrees C but not at 42 degrees C, and three of the isolates from two different patients were sensitive to nalidixic acid and cephalothin. Full 16S rRNA sequence analysis not only grouped these organisms within the Helicobacter genus but also differentiated them from previously identified Helicobacter species. The closest relative by phylogenetic analysis was Helicobacter sp. flexispira taxon 1. Electron microscopy showed that these isolates had one or two bipolar flagella; however, the periplasmic fibers, a characteristic of the known Helicobacter sp. flexispira taxa, were not observed. The present isolates also lacked a flagellar sheath, a trait shared with four other Helicobacter spp., H. canadensis, H. mesocricetorum, H. pullorum, and H. rodentium. On the basis of the unique phenotypic properties of these isolates and 16S rRNA sequence analysis, we propose the classification of a new Helicobacter species, Helicobacter winghamensis sp. nov.

FIG. 1

(A) Electron micrograph of H. winghamensis. Note unsheathed flagella (arrow) and a lack of periplasmic fibers on the surface of the organism. (B) Electron micrograph of Helicobacter sp. flexispira taxon 1 showing sheathed flagella (long arrow) and periplasmic fibers (short arrow).

FIG. 2

16S rRNA PCR-RFLP patterns for intestinal helicobacters generated using restriction enzyme BsrI. Lane 1, H. bizzozeronii; lane 2, H. canadensis; lane 3, H. canis; lane 4, H. cinaedi; lane 5, H. fennelliae; lane 6, H. pullorum; lane 7, Helicobacter sp. flexispira taxon 8; lane 8, H. winghamensis; lane M, 100-bp molecular weight marker (New England Biolabs)

FIG. 3

Phylogenetic dendrogram for Helicobacter. Numbers at nodes represent bootstrap support values (percentage of 1,000 resampled data sets that supported the node in the recalculated tree). Scale: 1.6 cm, approximate genetic distance of 0.01 base substitutions per nucleotide pair.