Novel urease-negative Helicobacter sp. ‘H. enhydrae sp. nov.’ isolated from inflamed gastric tissue of southern sea otters
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Author(s)
Batac, F
Miller, M. A.
Paster, B. J.
Shen, Zeli
Mannion, Anthony
Bakthavatchalu, Vasudevan
Ho, Calvin
Manning, Sean
Fox, James G
Date Issued
February 2017
Journal
Diseases of Aquatic Organisms
Publisher
Inter-Research Science Center
Citation
Shen, Z et al. “Novel Urease-Negative Helicobacter Sp. ‘H. Enhydrae Sp. Nov.’ Isolated from Inflamed Gastric Tissue of Southern Sea Otters.” Diseases of Aquatic Organisms 123, 1 (February 2017): 1–11
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Author's final manuscript
Abstract
A total of 31 sea otters Enhydra lutris nereis found dead or moribund (and then euthanized) were necropsied in California, USA. Stomach biopsies were collected and transected with equal portions frozen or placed in formalin and analyzed histologically and screened for Helicobacter spp. in gastric tissue. Helicobacter spp. were isolated from 9 sea otters (29%); 58% (18 of 31) animals were positive for helicobacter by PCR. The Helicobacter sp. was catalase- and oxidase-positive and urease-negative. By electron microscopy, the Helicobacter sp. had lateral and polar sheathed flagella and had a slightly curved rod morphology. 16S and 23S rRNA sequence analyses of all ‘H. enhydrae’ isolates had similar sequences, which clustered as a novel Helicobacter sp. closely related to H. mustelae (96-97%). The genome sequence of isolate MIT 01-6242 was assembled into a single ~1.6 Mb long contig with a 40.8% G+C content. The annotated genome contained 1699 protein-coding sequences and 43 RNAs, including 65 genes homologous to known Helicobacter spp. and Campylobacter spp. virulence factors. Histological changes in the gastric tissues extended from mild cystic degeneration of gastric glands to severe mucosal erosions and ulcers. Silver stains of infected tissues demonstrated slightly curved bacterial rods at the periphery of the gastric ulcers and on the epithelial surface of glands. The underlying mucosa and submucosa were infiltrated by low numbers of neutrophils, macrophages, and lymphocytes, with occasional lymphoid aggregates and well-defined lymphoid follicles. This is the second novel Helicobacter sp., which we have named ‘H. enhydrae’, isolated from inflamed stomachs of mustelids, the first being H. mustelae from a ferret. Keywords: Helicobacter; Gastritis; Otter
MIT Department
Massachusetts Institute of Technology. Department of Biological Engineering
Massachusetts Institute of Technology. Division of Comparative Medicine
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DOI of Published Version
https://doi.org/10.3354/dao03082
